Научная статья на тему 'NEW OPPORTUNITIES OF THE LA-ICP-MS APPLICATION FOR RESEARCH OF THE COMPOUND AND HOMOGENEITY OF TANTALUM BASED POWDER SAMPLES'

NEW OPPORTUNITIES OF THE LA-ICP-MS APPLICATION FOR RESEARCH OF THE COMPOUND AND HOMOGENEITY OF TANTALUM BASED POWDER SAMPLES Текст научной статьи по специальности «Медицинские технологии»

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Ключевые слова
LASER ABLATION / INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY / TANTALUM PENTOXIDE / LITHIUM TANTALITE / DOPING / RARE EARTH ELEMENTS

Аннотация научной статьи по медицинским технологиям, автор научной работы — Elizarova Irina R., Masloboeva Sofya M.

The article discusses the capabilities and features of the method of mass spectrometry with inductively coupled plasma and laser ablation (LA-ICP-MS), which is used to study the distribution of the dopant and determine the composition of powder samples of Ta2O5 precursors and a charge LiTaO3 doped with rare earth elements (TR = Pr, Nd, Sm, Eu, Gd, Dy). To determine the optimal parameters and adjust the mass spectrometer, laser evaporator and obtain calibration characteristics, we used standard SRM NIST 612 glass, a tableted sample of apatite concentrate 2462-82, and high-purity argon. It has been established that when using a tableted sample 2462-82, higher detection limits can be obtained, therefore it was used for the analysis of samples of solid precursors Ta2O5áTRñ and a charge LiTaO3áTRñ by the LA-ICP-MS method. The surface of the samples was scanned with a laser beam of various diameters from 20 to 350 μm with a laser radiation power of more than 1 W, a laser energy density of ≥ 15 J/cm2, sufficient for efficient evaporation of a pelleted sample. The laser pulse power was 40-80% of the possible value (1 W), the pulse repetition rate was 5-8 Hz. Using the Ta2O5áSmñ and LiTaO3áSmñ samples as examples, it has been shown that the Sm content determined by the LA-ICP-MS method corresponded to the specified one and has a high precision with the X-ray fluorescence method. The uniform distribution of the TR dopant in Ta2O5 and LiTaO3 is confirmed by the found values of the relative standard deviation of the intensity of the analytical signal Sr, which was 2-6 for the Ta2O5áTRñ powder samples, and 4-7 for the LiTaO3áTRñ charge. It is shown that the matrix effect is absent in the results of the analysis of powder samples by the LA-ICP-MS method; Ta2O5áTRñ samples prepared without a binder can be used for quantitative analysis of the LiTaO3áTRñ charge. The results obtained are important in the development of an effective technology for the synthesis of a charge of lithium tantalate doped with rare-earth elements, which is used to obtain homogeneous LiTaO3áTRñ single crystals of high optical quality. New possibilities of the proposed research method can be used for other powder materials tableted without a binder.

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Текст научной работы на тему «NEW OPPORTUNITIES OF THE LA-ICP-MS APPLICATION FOR RESEARCH OF THE COMPOUND AND HOMOGENEITY OF TANTALUM BASED POWDER SAMPLES»

DOI: 10.6060/ivkkt.20226504.6532

УДК: 681.7.069.24:661.888.3:66.046.516:661.865

НОВЫЕ ВОЗМОЖНОСТИ ПРИМЕНЕНИЯ МЕТОДА ЛА-ИСП-МС ДЛЯ ИССЛЕДОВАНИЯ СОСТАВА И ГОМОГЕННОСТИ ПОРОШКОВЫХ ПРОБ

НА ОСНОВЕ ТАНТАЛА

И.Р. Елизарова, С.М. Маслобоева

Ирина Рудольфовна Елизарова

Институт проблем промышленной экологии Севера - обособленное подразделение Федерального исследовательского центра "Кольский научный центр РАН", Академгородок, 14А, Апатиты, Мурманская обл., Российская Федерация, 184209 E-mail: [email protected]

Софья Михайловна Маслобоева*

Кафедра общих дисциплин, Филиал Мурманского арктического государственного университета в г. Апатиты, ул. Лесная, 29, Апатиты, Мурманская область, Российская Федерация, 184209 Институт химии и технологии редких элементов и минерального сырья им. И.В. Тананаева - обособленное подразделение Федерального исследовательского центра «Кольский научный центр Российской академии наук», Академгородок, 26а, Апатиты, Российская Федерация, 184209 E-mail: [email protected]*

В статье рассмотрены возможности и особенности метода масс-спектромет-рии с индуктивно связанной плазмой и лазерной абляцией (ЛА-ИСП-МС), применяемого для исследования распределения легирующей примеси и определения состава порошкообразных образцов прекурсоров Ta2Os и шихты LiTaOi, допированныхредкоземельными элементами (TR = Pr, Nd, Sm, Eu, Gd, Dy). Для определения оптимальных параметров и настройки масс-спектрометра, лазерного испарителя и получения градуировочных характеристик использованы стандартное стекло SRM NIST 612, таблетированный образец апатитового концентрата 2462-82 и высокочистый аргон. Установлено, что при применении таблетированного образца 2462-82 можно получить более высокие пределы обнаружения, поэтому он был использован для анализа проб твердых прекурсоров Та205(ТЯ)и шихты LiTaOs{TR) методом ЛА-ИСП-МС. Сканирование поверхности образцов осуществлялось лазерным пучком различного диаметра от 20 до 350 мкм с мощностью лазерного излучения более 1 Вт, плотностью энергии лазера > 15 Дж/см2, достаточной для эффективного испарения таблетированной пробы. Мощность лазерного импульса составляла 40-80% от возможной величины (1 Вт), частота следования импульсов - 5-8Гц. На примере образцов Та205^т)и LiTaOi(Sm) показано, что содержание Sm, определенное методом ЛА-МС-ИСП, соответствовало заданному и имеет высокую прецизионность с рентгенофлуоресцентным методом. Равномерное распределение легирующей примеси TR в Та205 и LiTaOi подтверждено найденными значениями относительного стандартного отклонения интенсивности аналитического сигнала Sr, которое для порошковых образцов Та205{TR) составило 2-6, для шихты LiTaOi(TR)- 4-7. Показано, что матричный эффект отсутствует в результатах анализа порошкообразных образцов методом ЛА-ИСП-МС; образцы Та205(TR), изготовленные без связующего, могут быть использованы для количественного анализа шихты LiTaOi(TR). Полученные результаты имеют важное значение в разработке эффективной технологии синтеза легированной редкоземельными элементами шихты танталата лития, используемой для получения однородных монокристаллов LiTaOs(TR) высокого оптического качества. Новые возможности предложенного метода исследования могут быть использованы для других порошковых материалов, таб-летированных без связующего компонента.

Ключевые слова: лазерная абляция, масс-спектрометрия с индуктивно связанной плазмой, пен-таоксид тантала, танталат лития, легирование, редкоземельные элементы

Для цитирования:

Елизарова И.Р., Маслобоева С.М. Новые возможности применения метода ЛА-ИСП-МС для исследования состава и гомогенности порошковых проб на основе тантала. Изв. вузов. Химия и хим. технология. 2022. Т. 65. Вып. 4. С. 13-21 For citation:

Elizarova I.R., Masloboeva S.M. New opportunities of the LA-ICP-MS application for research of the compound and homogeneity of tantalum based powder samples. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2022. V. 65. N 4. P. 13-21

NEW OPPORTUNITIES OF THE LA-ICP-MS APPLICATION FOR RESEARCH OF THE COMPOUND AND HOMOGENEITY OF TANTALUM BASED POWDER SAMPLES

I.R. Elizarova, S.M. Masloboeva

Irina R. Elizarova

Institute of North Industrial Ecology Problems, Subdivision of the Federal Research Centere "Kola Science Centre of the Russian Academy of Sciences", Akademgorodok, 14A, Apatity, Murmansk region, 184209, Russia E-mail: [email protected]

Sofya M. Masloboeva*

Department of General Disciplines. Apatity branch of Murmansk Arctic State University, Lesnaya st., 29, Apatity, Murmansk region, 184209, Russia

Tananaev Institute of Chemistry - Subdivision of the Federal Research Centre Kola Science Centre of the RAS, Science Centre of the RAS, Akademgorodok, 26a, Apatity, 184209, Russia E-mail: [email protected]*

The article discusses the capabilities and features of the method of mass spectrometry with inductively coupled plasma and laser ablation (LA-ICP-MS), which is used to study the distribution of the dopant and determine the composition ofpowder samples of Ta2Os precursors and a charge LiTaOi doped with rare earth elements (TR = Pr, Nd, Sm, Eu, Gd, Dy). To determine the optimal parameters and adjust the mass spectrometer, laser evaporator and obtain calibration characteristics, we used standard SRM NIST 612 glass, a tableted sample of apatite concentrate 2462-82, and high-purity argon. It has been established that when using a tableted sample 2462-82, higher detection limits can be obtained, therefore it was used for the analysis of samples of solid precursors Ta2Os{TR) and a charge LiTaOs(TR) by the LA-ICP-MS method. The surface of the samples was scanned with a laser beam of various diameters from 20 to 350 pm with a laser radiation power of more than 1 W, a laser energy density of > 15 J/cm2, sufficient for efficient evaporation of a pelleted sample. The laser pulse power was 40-80% of the possible value (1 W), the pulse repetition rate was 5-8 Hz. Using the Ta2O5{Sm)andLiTaO3{Sm) samples as examples, it has been shown that the Sm content determined by the LA-ICP-MS method corresponded to the specified one and has a high precision with the X-ray fluorescence method. The uniform distribution of the TR dopant in Ta2O5 and LiTaO3 is confirmed by the found values of the relative standard deviation of the intensity of the analytical signal Sr, which was 2-6 for the Ta2O5(TR) powder samples, and 4-7 for the LiTaO3(TR) charge. It is shown that the matrix effect is absent in the results of the analysis of powder samples by the LA-ICP-MS method; Ta2O5(TR) samples prepared without a binder can be used for quantitative analysis of the LiTaO3(TR) charge. The results obtained are important in the development of an effective technology for the synthesis of a charge of lithium tantalate doped with rare-earth elements, which is used to obtain homogeneous LiTaO3(TR) single crystals of high optical quality. New possibilities of the proposed research method can be used for other powder materials tableted without a binder.

Key words: laser ablation, inductively coupled plasma mass spectrometry, tantalum pentoxide, lithium tantalite, doping, rare earth elements

INTRODUCTION

Creation of optical materials technology based on optically nonlinear crystals doped by rare-earth elements is a task of great practical importance. Single crystal lithium tantalate is of the most perspective ferroelectric materials. It arises such scientific interest because it combines unique electrooptical, optically nonlinear and laser properties [1-3]. It is a well known fact that doping with lithium tantalate changes the optical and electro-physical properties of single crystals. The research of lithium niobate single crystals [4] revealed the following: not only concentration and type of dopant influence crystals characteristics, but also doping method. Today the problem stays unsolved for lithium tantalate crystals. The method of lithium tantalate crystals doping by rare-earth elements is described in detail in [5]. The research highlights importance of chemical uniformity at a distribution of the dopant, starting from making of a precursor.

The dopant concentration in Ta2Os and LiTaO3 is usually detected in their acid solutions [6]. This analysis technique is able to obtain results for a usual sample amount 50-100 mg, i.e. a macro-volume. However, control of distribution of a single component in a micro-volume sample (less than 0.1 mg) is still an unsolved problem. This is the reason why it should be actual.

Today the amount of laboratories equipped by laser ablation inductively coupled plasma mass spectrometers (LA-ICP-MS method) rises. LA-ICP-MS is able to obtain instrumental response along the depth profile (up to 0.2-0.3 ^m during one laser impulse) and on the flat sample surface at the analysis of a sample dry aerosol, evaporated by energy of a laser beam 20350 ^m in diameter. A structure of a solid sample, chemical compound, surface condition and the laser ablation parameters are crucial at laser evaporating of a sample. The parameters are radiation power, duty cycle and a laser beam diameter [7]. The research [7] concluded that laser energy parameters, repetition speed and the crater size bounded by an aperture determine the speed of the material evaporation. A change of the power by an energy attenuator controls the laser energy. A change in a repetition frequency programmed by software influences the speed of the evaporation. The frequency less 10 Hz is used for "soft" materials, such as powders, to provide optimal intensity of the evaporated material flux. For example, glasses or geological samples can be analyzed with the frequency 10 Hz. Authors of [7] emphasize that the repetition frequency should be adjusted for each matrix type. The authors of [8] used the laser ablation method to create textures on the surface of polytetrafluoroethylene. The

works [9-11] describe the possibilities of using LA-ICP-MS for the analysis of powdered samples of tablet form with and without a binder.

Authors [9, 12] stress that effects of an element fractioning have a significant impact on instrumental response of the device at the stage of melting, evaporating, a sample transport to the plasma torch of mass spectrometer. In the works [13-18] confirm the previous conclusions for research of such transparent materials as calcite, silicate glass etc.

LA-ICP-MS is sensitive towards compound and micro-homogeneity of a standard sample. Such sample could be used for setting and optimizing mass spectrometer operating parameters and for obtaining of calibration curves. Authors of [5, 19-20] solved the problem of sample choice to calibrate laser evaporator and mass spectrometer parameters. The authors revealed that a tableted sample made of a geological standard (for example, an apatite concentrate) is suitable for these purposes.

Thus a complex approach to the laser evaporation parameters choice must take into account the requirements of the analytical problems to be solved and particularities of an object of study. This is necessary to achieve the best accuracy of analysis and the lowest detection limits. The experience in use of LA-ICP-MS gives an ambiguous choice of conditions for research of compound and chemical homogeneity of samples. This fact determines actuality of solving the problem of choice of standard and reference samples for the LA-ICP-MS analysis. This problem has been little studied for powdered tableted samples.

This paper tests the possibility to use an LA-ICP-MS in a completely new application - research of a micro-homogeneity of a sample with a simultaneous detection of a dopant concentration.

MATERIALS AND METHODS

Concentrations of analytes were detected by a mass-spectrometer method (ELAN-9000 DRC-e, Per-kin Elmer, USA). A sample material was taken locally from the surface by a laser sampler UP-266 MACRO (New Wave Research, USA), using a laser ablation process. Laser radiation used in experiments was Nd:YAG (X0 = 266 nm). Determination of optimal conditions for a standard silicate sample (glass) SRM NIST 612 [21] sampling was necessary to provide stability of instrumental response of an interrelated complex that includes a laser evaporator and a mass-spectrometer. Al and Si were chosen as analytes for LA-ICP-MS parameters optimization. Al and Si concentration in SRM NIST 612 were 33.6% and 1.1%, respectively. Laser beam diameters were chosen to be 20-350 ^m

among all possible values. Use of bigger diameters is undesirable because drift of intensities appears. Tab-leted samples Ta2O5<TR> h LiTaO3<TR> (TR = Pr, Nd, Sm, Eu, Gd, Dy) without the binder 12 mm in diameter were obtained under identical and repeatable conditions by pressing in a metal shell under pressure ~106 Pa. The powder was not mixed or rubbed before tableting. A mass-spectrometer parameters were the following: Neb. Gas Flow = 0.08 - 1.00 l/min, ICP RF Power = 1250.00 - 1350.0 W, Analog Stage Voltage = -1800.00 - -1900.00 V, Pulse Stage Voltage = 850.00 - 950.00 V. High-purity argon (not less than 99,995 wt. %) was used as a blank. A mode "jump on peaks" was used during analysis automatically, which means that method file contained: 3 jumps on the peak, 3 scans on the peak, 3 replicas of mass spectrum scanning. A microscope Leica DM2500 was used to measure LA craters diameter and evaluate their shape.

RESULTS AND DISCUSSION

We have detected a ration between physical parameters of LA and their influence on intensity of the instrumental response (i.e a number of electrical impulses registered by a detector per second). The instrumental response intensity was determined to be connected with a laser beam diameter, laser impulses frequency and laser radiation power. A change in a laser impulses frequency fails to influence energy of laser beam that reaches the sample. Whereas an increase in a laser beam diameter does increase this parameter. Laser radiation energy follows a saturation curve at a power increase to 100%. Energy that reaches the sample increases with an increase in laser beam diameter in both cases. Such interrelation reflects technical parameters of UP-266 MACRO. Obtained dependences helped to choose a laser beam diameter and power necessary to supply a sample by enough energy at analyses.

We adjusted the device using LA attachment both at mass-spectrometry analysis and analysis of solutions. We have detected that functional dependence of the ion lens voltage on the analyte mass is free of fundamental differences from the same dependence obtained at use of calibration solutions. The differences are absent at adjusting of resolving power (mass scale) in LA-ICP-MS and ICP-MS experiments.

During adjusting of parameters of mass-spectrometer and laser evaporator, and obtaining of calibration characteristics we have replaced the standard glass SRM NIST 612 with a tableted sample from a powder geological standard sample of apatite concentrate 2462-82 (composition and determination error of ana-

lytes are presented in Table 1). An adjustment procedure was carried out according to the geological standard according to the scheme recommended by the manufacturer. Use of tableted sample enables achieving of higher detection limits [19]. We assume that this is a result of more active emission of material from powder samples, but the reasons are a matter of future study.

The final stage of routine daily adjustment of the mass spectrometer tuning is determination of the LenzDac parameter, which links the pulse and analog segments of the detector to the mass of isotopes selected for tuning. Adjustment characteristics were similar to the ones obtained at adjustment using SRM NIST 612.

Table 1

Composition of geological standard sample of apatite concentrate 2462-82, certified by Institute of mineralogy, geochemistry and crystal chemistry of rare elements (Moscow, Russia) Таблица 1. Состав геологической эталонной пробы апатитового концентрата 2462-82, аттестованной Институтом минералогии, геохимии и кристаллохи-

мии редких элементов (Москва, Россия)

The component Weight fraction of component. % An absolute measurement error (%) with a 0.95 confidence interval

SiO2 2.07 0.15

TiO2 0.44 0.01

CaO 50.66 0.28

MgO 0.081 0.012

P2O5 39.27 0.27

MnO 0.039 0.004

Na2O 0.43 0.04

K2O 0.18 0.02

SrO 2.61 0.18

Fe 0.46 0.02

F 3.14 0.04

STR2O3 0.83 0.04

La2O3 0.24 0.03

CeO2 0.36 0.03

Pr2O3 0.040 0.006

Nd2O3 0.14 0.01

Sm2O3 0.021 0.004

Eu2O3 0.0058 0.0011

Gd2O3 0.022 0.006

Tb2O3 0.0018 0.0006

Dy2O3 0.0078 0.0017

Yb2O3 0.0014 0.0004

Y2O3 0.040 0.005

A laser beam of different diameters scanned surfaces of tableted samples. Diameter was from 20 to 350 ^m, laser radiation power was upper than 1 W, laser energy density > 15 J/cm2. Such density is enough

for effective evaporation of a tableted sample. Pulse power was 40-80% of a possible value (1 W), pulses frequency was 5-8 Hz.

The sample evaporates under the laser beam. Power, energy and the laser beam spot area are determined by LA processes parameters. The choice of parameters influences quality, repeatability of the shape and volume of the crater; thus it influences the amount of material evaporated during one pulse. This determines intensity of the instrumental response, thus limits of elements detection. It is important to ensure that consecutive pulses form strictly cylindrical craters of the exact diameter. The beam shape can be other than a circle, but it is crucial that the shape and proportion should stay the same. Otherwise reproducible results and calibration dependencies are impossible to achieve because amount of evaporated during one sampling act material will considerably vary.

In the process of examining samples Ta2O5<TR) h LiTaO3<TR) laser ablation is most effective in comparison with other methods of their decomposition (acidic, melting followed by leaching, autoclave). Standard samples of similar composition necessary for obtaining of calibration curves are absent. This is the main problem of LA-ICP-MS analysis of solid precursors Ta2O5<TR) and LiTaO3<TR) charge. In order to solve this problem we considered a possibility to use tableted samples of an apatite concentrate 2462-82 with certified values (wt.%): PftO3 = 0.040, Nd2O3 = 0.14, Sm2O3 = 0.021, Eu2O3 = 0.0058, Gd2O3 = 0.022, Dy2O3 = 0.0078. Besides, study of micro-homogeneity and composition of samples can be carried out by scanning of the sample surface with a laser beam or a layer-by-layer analysis during laser sampling in one point. Such analysis is carried out firs of all to detect a dopant concentration. The method minimizes experiment method due to absence of decomposition or dissolving stage. The stage provides possibility to loose or add something. Most of spectral poly-atomic overlap is excluded when liquid phase is absent from the sample flow in a plasma torch of a mass-spectrometer.

Unlike analysis of tantalum-containing samples solutions, at use of LA-ICP-MS for analysis of solid tableted samples of precursor and charge the matrix effect was absent, or at least we did not detect it. At analysis of tableted tantalum pentoxide sample containing 1 wt. % TR this ratio never exceeded 40, even at use of 100% of laser power. Thus we have detected that the tantalum amount exceeding TR amount did not suppress instrumental response of TR. The absence of the matrix effect at is another advantage of LA-ICP-MS analysis of tableted samples.

The approached were identical at analyses of precursors Ta2O5<TR) and LiTaO3<TR) charge. We have demonstrated them on the examples containing Sm as a dopant. Fig. 1 demonstrates craters after the LA of a tableted sample of an apatite concentrate 246282 and Ta2O5<Sm) (1.0 wt. %) at an increase in the pulse amount from 10 to 1000.

We found that an increase in the pulse amount does not lead to a distortion of cylindrical shape of craters and their diameters. Measurements on a microscope Leica DM2500 P has shown that craters have average diameters 105±2.97 ^m (relative standard deviation 1.72). Use of 100% power of laser radiation leads to over-heating of a sample's upper layers, spreading, cracking and crumbling of material which leads to an increase in dispersity of reproducibility of results.

п HI: Ж ? 11

□ f " 'iv □ a □

в ■ .-'Я *4 JP K: >&A v- ■к • • ЧЯ- i > i \ i '*? 'A

□ - □ Q 1 . □

Fig. 1. Craters after laser ablation of tableted samples: 1 - apatite concentrate 2462-82, 2 - Ta2O5(Sm) (1.0 wt. %); a - a single impulse, b - 10, c - 50, d - 1000 pulses. Power and frequency of impulses were 60% and 5 Hz, laser beam diameter was 100 ^m Рис. 1. Кратеры после лазерной абляции таблетированных образцов: 1) ГСО 2462-82 (апатитовый концентрат), 2) Та2O5(Sm) (1,0 мас.%); а - единичный импульс, b - 10, с - 50, d - 1000 импульсов. Мощность и частота следования импульсов, соответственно, 60% и 5 Гц, диаметр лазерного пучка 100 мкм

A dependence on Fig. 2 was obtained due to the use of tableted apatite concentrate 2462-82 for drawing of a calibrating characteristics (a number of measurements n = 4) during registration of a massspectrum in the mode "jumping from peak to peak" (3 jumps on the peak, 3 scans on the peak, 3 replicas of mass spectrum scanning). A quantitative LA-ICP-MS analysis of a tantalum pentoxide doped by samarium sample was carried out using a calibration dependence on Fig. 2 and other calibration dependences obtained for 147Sm, 149Sm, 150Sm, 154Sm. We used GSO 2462-82 tableted powder for calibration and then analyzed a sample of Ta2O5 doped with samarium. That is, the analysis involved samples of different phase and chemical composition. New possibilities of the proposed research method can be used for other powder materials tableted without a binder. Table 2 demonstrates the results.

The LA-ICP-MS analysis has demonstrated a high precision (the degree of proximity of the results of the analysis obtained by independent methods in specific regulated conditions) with a X-ray fluorescence method: the results corresponded to given values of samarium concentrations detected due to the weight of dopant added at the Та2O5<Sm) precursor synthesis stage (Table 2).

Fig. 3 demonstrates calibration function of 152Sm. It was built using a number of Та2O5<Sm) charge powder tablets. We have obtained analogues dependences for isotopes 147Sm, 149Sm, 150Sm, 154Sm. We have also found equations of calibration dependences: for 147Sm Int (imp/s)=(5.6818±0.0567) • CSm(ppm), R=0.999255, for 149Sm R=0.999120, for 150Sm

R=0.999388, for 152Sm

R=0.999563, for 154Sm

R=0.999363,

where R is a coefficient of approximation of a linear calibration function, 1 ppm=10-4 wt.%.

Int (imp/s)=(5.1059±0.0553) • Csm(ppm) Int (imp/s)=(2.6770±0.0242) Int (imp/s)=(9.3591±0.0715) Int (imp/s)=(7.6194±0.0702) • Csm(ppm)

Csm(ppm), (1)

Csm(ppm),

Concentration,

Fig. 2. Calibration dependence for 152Sm, obtained using tableted apatite concentrate 2462-82 with the content 0.021 wt.% of Sm2Û3

Рис. 2. Градуировочная зависимость для 152 Sm, полученная с использованием таблетированного ГСО 2462-82, содержащего 0,021 мас.% Sm2Û3

We have confirmed chemical composition of Та20б^т). This is the reason why these samples were used as standards for the construction of calibration characteristics at detection of samarium concentration in the LiTa03<Sm) charge samples. A Та205<Sm) nature is close to the one of LiTa03<Sm), this determines why we prefer a Та205<Sm) standard to apatite concentrate 2462-82.

Concentration,

Fig. 3. A dependence of instrumental response intensity for 152Sm

on samarium concentration in tableted samples Ta2O5(Sm) Рис. 3. Зависимость интенсивности аналитического сигнала 152Sm от концентрации самария в таблетированных пробах Td205<Sm)

Table 2

Results of samarium detection in researched samples

Та2O5<Sm> LiTaO3<Sm>

Given concentration, wt.% According to LA-ICP-MS analysis, wt.% Relative standard deviation Sr, % According to X-ray fluorescence analysis, wt.% Given concent-ration*, wt.% According to LA-ICP-MS analysis, wt.% Relative standard deviation Sr, % According to X-ray fluorescence analysis, wt.%

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0.1 0.105 3.25 0.093 0.094 0.095 6.69 0.104

0.5 0.494 4.19 0.480 0.470 0.446 5.08 0.453

1.0 0.988 2.00 0.972 0.940 0.918 4.00 0.894

1.5 1.560 2.55 1.429 1.410 1.375 4.09 1.420

Note: * Concentration values were calculated according to the given Sm concentration in Та2О5 in LiTa03 charge of congruent composition (molar ratio |Ъ^/[Та]=0.9417)

Примечание: * Значения концентрации рассчитаны по заданной концентрации Sm в Та2О5 в шихте LiTaO3 конгруэнтного состава (мольное отношение [Ь1]/[Та]=0,9417)

A ration of natural samarium isotopes in a row 150Sm:149Sm:147Sm:154Sm:152Sm corresponds to 1:1.87:2.03:3.08:3.62. A ratio between angular coefficients of dependences (1) was 1:1.91:2.12:2.85:3.50 in this row. This fact together with extrapolation to the

coordinate basic origin confirmed the correctness of obtained approximations and the correctness of use of tableted powder apatite concentrate 2462-82 for the LA-ICP-MS analysis. We have used equations (1) for a quantitative LA-ICP-MS analysis of LiTa03<Sm).

A uniformity of TR distribution was proved by a relative standard deviation Sr of the instrumental response intensity measured in the experiment on research of dopant microhomogeneity. A relative standard deviation characterized both homogeneity of the analyte distribution and a standard deviation of the instrumental measurements. Table 2 demonstrates Sr values for samples with Sm. A figure in [5] demonstrates a change in the instrumental response for different isotopes during the LA-ICP-MS analysis for samarium. Graphical data obtained due to an analogues method for dysprosium is demonstrated on Fig.4.

A dispersity of reproducibility of the instrumental response intensity detected from the value of relative standard deviation: did not depend on the velocity and step length of the scanning; did not exceed the dispersity obtained at analysis of a chemically uniform standard SRM NIST 612; did not exceed the dispersity obtained at LA-ICP-MS analysis of glasses and geological samples. The sum of these features confirms chemical uniformity the macro-dopant in researched samples Ta2O5 and LiTaO3.

The graphs had the same character at analysis of all samples containing TR. For the Ta205<TR) samples Sr (%) parameter was 2-6, for LiTa03<TR) charge - 4-7, which is lower than analysis error (up to 10%). This confirms chemical uniformity of TR distribution in samples under consideration.

CONCLUSION

Working parameters of LA was shown to be interconnected at the LA-ICP-MS analysis. Powder samples of Та205<TR) precursor created without a binder can be used for the quantitative LA-ICP-MS analysis of doped lithium tantalate charge. Results obtained by the LA-ICP-MS analysis were confirmed by X-ray fluorescent method and coincide well with it. Та205<TR) precursors and LiTa03<TR) charge have revealed that dopant distribution is chemically uniform. An absence of a matrix effect of tantalum on the instrumental response intensity was detected at analysis of tableted samples.

ЛИТЕРАТУРА

1. Кузьминов Ю.С. Ниобат и танталат лития - материалы для нелинейной оптики. М.: Наука. 1975. 224 с.

2. Бузанов О.А., Сахаров С.А., Рощупкин Д.В., Емелин Е.В., Лавров С.Д. LiTa03 - многофункциональный материал опто- и акустоэлектроники. Изв. высш. учебн. за-вед. Матер. электрон. техники. 2013. N° 3. С. 24-27. D0I: 10.17073/1609-3577-2013-3-24-27.

3. Кубасов И.В., Кислюк А.М., Турутин А.В., Малинко-вич М.Д., Пархоменко Ю.Н. Бидоменные сегнетоэлек-трические кристаллы: свойства и перспективы применения. Изв. высш. учебн. завед. Матер. электрон. техники. 2020. Т. 23. №° 1. C. 5 - 56. D0I: 10.17073/1609-3577-20201-5-56.

0 200 400 600 1, s

8- b '[линю

О 100 200 300 t, s

Fig. 4. The change in instrumental response intensity of Dy isotopes at stepwise laser ablation (a step was 7-9 ^m) across the tablets sample surface: a - Ta205<1.5 wt.% Dy), b - LiTa03<1.35 wt.% Dy). A laser beam diameter was 100 ^m, laser impulses frequency was 5Hz, laser pulse power was 60% Рис. 4. Изменение интенсивности аналитического сигнала изотопов Dy при пошаговой лазерной абляции (шаг 7-9 мкм) по поверхности таблетированного образца: а - Ta205(1,5 мас.% Dy), b - LiTaC>3(1,35 мас.% Dy). Диаметр лазерного пучка 100 мкм, частота следования импульсов 5 Гц, мощность лазерного импульса 60%

C0NFLICT 0F INTERESTS

The authors declare the absence a conflict of interest warranting disclosure in this article.

Авторы заявляют об отсутствии конфликта интересов, требующего раскрытия в данной статье.

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Поступила в редакцию 15.10.2021 Принята к опубликованию 24.02.2022

Received 15.10.2021 Accepted 24.02.2022

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