A Study of Electrical Conductivity in Concentrated Solid Solutions ca1−xLnxF2+x (Ln = La, Gd, Er, Y)

Švantner, M.; Mariani, E.; Федоров, П. П.; Соболев, Б. П.

doi:10.1002/crat.19810160515

Cited by 17 publications

(2 citation statements)

References 10 publications

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“…Ионная проводимость [11][12][13][14][15][16][17][18] и дефектная структура [19][20][21][22][23][24] кристаллов твердого электролита Ca 1−x Y x F 2+x активно исследуются. Однако в проведенных исследованиях концентрационная зависимость проводимости в области состава с конгруэнтным плавлением детально не изучалась, совместное комплексное изучение кондуктометрических и структурных особенностей этих кристаллов, выполненные на одних и тех же образцах, не рассматривалось.…”

Section: ни сорокин дн каримовunclassified

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Сорокин¹,

Каримов²

2021

Физика Твердого Тела

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Based on the electrophysical and structural data, a crystallophysical model of ion transfer in superionic conductors Ba1-xLaxF2 + x and Ca1-xYxF2 + x (space group Fm3m) is proposed, in which the charge carriers are mobile interstitial ions Fmob-, formed as a result of heterovalent substitutions of fluorite fragments [M14F64] (M = Ca, Ba) into structural clusters [M8R6F69] (R = La, Y). Single crystals of solid solutions Ca1-xYxF2 + x (0.02≤ x≤0.16) and Ba1-xLaxF2 + x (x = 0.31) were obtained by directional crystallization of the melt. The mobilities of ionic carriers in isostructural superionics Ba0.69La0.31F2.31, Ca0.84Y0.16F2.16, Pb0.67Cd0.33F2, and Pb0.9Sc0.1F2.1 are compared. Crystals Ba1-xLaxF2 + x and Ca1-xYxF2 + x with improved conductometric and mechanical characteristics are promising for replacing the traditional CaF2 electrolyte in galvanic cells for thermodynamic research of chemicals.

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Section: ни сорокин дн каримовunclassified

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Сорокин¹,

Каримов²

2021

Физика Твердого Тела

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“…Studies of fluoride ion transport in M I -N2+x crystals as a result of disturbed atomic structure (anionic motif) is one of the most complete programs which describe grossly nonstoichiometric fluoride materials [46][47][48][49][50][51][52][53][54][55][56]. where the effect of structural defectiveness of the phases on the ionic conduction has been shown to be .…”

Section: Chemical Processes During Mixture Preparation and Growthmentioning

confidence: 99%

Preparation of Single Crystals of the Nonstoicmometric Fluorite Phases M1-xRxF2+x (M = Ca, Sr, Ba; R = Rare Earth Elements) by the Bridgman-Stockbarger Method

Соболев¹,

Жмурова²,

Karelin³

et al. 1991

Growth of Crystals

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INTRODUCTIONResearch on the preparation and study of single-crystalline M 1 -N2+x (R = rare earth element, REE) materials with large deviations from stoichiometry began at the Institute of Crystallography of the Academy of Sciences of the USSR in 1963. The efforts were continued in cooperation with the chemistry staff of Moscow State University. Progress on the quest and preparation of crystals of nonstoichiometric fluorides for quantum electronics up to 1978 was reviewed in dissertations [2]. However, a large part of the data on growth of M 1 -N2+x single crystals is scattered over a large number of obscure publications.The purpose of the present article is to review and correlate all work published by us on the growth of M 1 -xRxf'2+x fluorite phase crystals.The uniqueness of this family of crystals and hence the unwavering interest in their preparation and study consists in the gross deviations from stoichiometry which permit fluorite structural types with heterovalent substitution of M2+ by R3+ (up to 50 mole % RF 3 ). Changes in the physical and physicochemical characteristics of the crystals are effected and controlled as a result of the gross nonstoichiometry. Mechanical, radiative, thermal, chemical, optical, transport, acoustic, and other structurally sensitive characteristics are affected.The M 1 -xRxf'2+x phases are the most striking with respect to nonstoichiometry and most feasible from the viewpoint of technological production among the more than 150 types of known fluorites with gross stoichiometric imbalance [1]. Numerically, they comprise a third of all known types (according to qualitative chemical compOSition) of fluorite-fluoride nonstoichiometric (two-component) phases.The scope of our program characteristically includes preparation of single crystalS of the M 1 -xRxf'2+x nonstoichiometric fluorite phases for the whole concentration region covering hundredths of a fraction of a percent to saturation, i.e., -50 mole % RF 3 . Numerous publications by other authors have appeared for REE trifluoride concentrations of 1-3 mole %. Review of these is a separate task. Few articles can be singled out on the preparation of single crystals with high contents of RF 3 . The most systematic of these should be mentioned [3][4][5][6]. In particular, the high content of heterovalent impurities in the CaF 2 structure is of prime 65 K. S. Bagdasarov et al. (eds.), Growth of Crystals

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Effect of ROF impurities on electrical, mechanical, and optical characteristics of CaF₂ single crystals

Федоров

Gorbulev

Mariani

et al. 1981

Cryst Res and Technol

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Earlier solid solutions of ROF in CaF, with a content of ROF up to 0.2 wt % were investigated by the spectroscopical (FEOFILOV 1954; KAPLYANSKY) and ESR methods (SIWRO).The investigations of more concentrated solid solutions were kept back by difficulties in producing single crystals. As a result of the investigation of phase diagrams ( GORBULEV et al. 1981GORBULEV et al. , 1981 we have ascertained that on the basis of CaF, the ROF components form vast areas of solid solutions of the general formula Ca, -,R,F2 -xO, containing up to 45 mol % LaOF, 40 mol% GdOF, 25 mol% YOF. However, with a decrease in temperature the areas of homogeneity in the solid solutions sharply get narrow.The objective of the present paper was to grow CaF, single crystals with a great content of ROF and investigate some of their physical properties. Methods and resultsThe growing of single crystals was carried out by the Bridgman method in graphite crucibles in an atmosphere of helium of high purity. The pulling rate made up 10 or 25 mm/h. As starting components CaF, in the form of single crystals and ROF oxyfluorides were used. ROF had been synthesized beforehand by sintering oxides, Grade "OOO", and fluorides of high purity, i. e. "chemically pure". When the crystals were slowly cooled to room temperature an opacity of the crystals was observed due to the second phase precipitation already at a contem of 1 mol% ROF. With a view to prevent the solid solution decomposition we have used a quick cooling of crystals (at a rate of 1 -5"/sec) from the temperature exceeding the solid solution decomposition curve (800-1200 "C for different compositions).Thus, colourless transparent single crystals containing up to 5 mol% ROF were produced. The crystals were retained in the metastable state when stored at room temperature during one and a half year without becoming opaque. 1 -CaF,; 2 -98% CaF, -2% LaOF; 3 -99% CaF, -I % GdOF; 4 -95% CaF, -5 % GdOF; 5 -95%CaF2 -5 % LaOF; 6 -98%CaF, -2% YOF; (mol %) The IR spectra of,the single crystals produced within a range of 2-10 pm were recorded by a UR-20-type spectrometer.It has been found that the spectra ofcrystals containing ROF practically do not differ from the pure fluorite spectrum. Thus, crystals Ca, -.R,F, -xO, retain transparency in the IR region irresptive of the ROF content.Knoop Microhardness has been measured by a PMT-3-type hardometer at a load of 100 g. The results are given in Figure I. A considerable increase in microhardness takes place in the solid solution with an increase in the ROF content.Electrical conductivity of samples has been measured at a vacuum of lo-' torr in the temperature interval of 293-973 K using a Va-J-51-type, D.C. electrometer. In addition, measurements have been carried out

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A Study of Electrical Conductivity in Concentrated Solid Solutions ca_1−xLn_xF_2+x (Ln = La, Gd, Er, Y)

Cited by 17 publications

References 10 publications

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Preparation of Single Crystals of the Nonstoicmometric Fluorite Phases M1-xRxF2+x (M = Ca, Sr, Ba; R = Rare Earth Elements) by the Bridgman-Stockbarger Method

Effect of ROF impurities on electrical, mechanical, and optical characteristics of CaF₂ single crystals

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A Study of Electrical Conductivity in Concentrated Solid Solutions ca1−xLnxF2+x (Ln = La, Gd, Er, Y)

Cited by 17 publications

References 10 publications

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Preparation of Single Crystals of the Nonstoicmometric Fluorite Phases M1-xRxF2+x (M = Ca, Sr, Ba; R = Rare Earth Elements) by the Bridgman-Stockbarger Method

Effect of ROF impurities on electrical, mechanical, and optical characteristics of CaF2 single crystals

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A Study of Electrical Conductivity in Concentrated Solid Solutions ca_1−xLn_xF_2+x (Ln = La, Gd, Er, Y)

Effect of ROF impurities on electrical, mechanical, and optical characteristics of CaF₂ single crystals