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Валеева, А. А.; Rempel, А. А.; Гусев, А. И.

doi:10.1023/a:1017568301183

Cited by 86 publications

(66 citation statements)

References 13 publications

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“…Микрокристаллические порошки монооксида титана TiO у синтезированы методом твердофазного спекания в вакууме из смеси порошков металлического титана Ti и диоксида титана TiO 2 , проведена аттестация образцов монооксида титана по химическому и фазовому составу, степени гомогенности и типу кристаллической структу-ры [10].…”

Section: материалыunclassified

Development of a biomaterial based on HAP/TiOy nanocomposite with different stoichiometry

Rempel¹,

Валеева²,

Богданова³

et al. 2017

LoM

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At present, composite materials based on bioactive hydroxyappatite (HAP) are intensively developed. To achieve better mechanical properties, different additives are used, for example, titanium, zirconium, etc. In the present study, a dispersionhardened composite material based on nanocrystalline HAP and nanocrystalline titanium monoxide (TiO y , y = 0.92, 1.23) is prepared by low temperature annealing in vacuum. As an additive, titanium monoxide with different mass ratios and stoichiometries (10 or 20 mass % of substoichiometric TiO 0.92 or superstoichiometric TiO 1.23 ) is used. For the preparation of nanocrystalline powders and mixing of initial components, a planetary ball mill was used. According to scanning electron microscopy (SEM) data, using of the ball milling for mechanical mixing of nanopartilces allows one to prepare denser material with a particle shape, which facilitates cold pressing and sintering. It has been established that introducing of the TiO y additive leads to a reduction of the starting temperature of the composite material hardening by 200 to 250°С. The phase composition and properties of the end product (microhardness, density) depend on the stoichiometry and on the amount of additives. For the content of 20 mass % of substoichiometric TiO 0.92 phases Ti 4.5 O 5 and Ti 6 O 11 are found by means of XRD studies. The phase Ti 4.5 O 5 is an ordered phase and is more stable as compared to other phases of Ti-O system., while the phase Ti 6 O 11 has easy slip crystallographic planes. Presence of such two phases positively influences on mechanical properties of the composite. According to SEM, BET and microhardness data, the composites prepared are nanodispersed ones and show an increased density and microhardness as compared to HAP without additives. Ключевые слова: гидроксиапатит, монооксид титана, размол, отжиг, микротвердость.

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Section: материалыunclassified

Development of a biomaterial based on HAP/TiOy nanocomposite with different stoichiometry

Rempel¹,

Валеева²,

Богданова³

et al. 2017

LoM

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“…Their percent age can be up to 32 at % [1][2][3][4]. In the case of an equi atomic composition, the amount of vacancies is about 14-15 at % in each sublattice [3,4].…”

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confidence: 99%

“…Vacancies may be located over sites of the basic В1 structure either randomly or in an ordered manner. The disordered state is thermody namically stable at temperatures above 1300 K, but it can be obtained at room temperature by quenching [3,4]. Since the vacancies are chaotically located, the X ray diffraction patterns of disordered samples exhibit only characteristic of the cubic B1 structure.…”

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confidence: 99%

“…Since the vacancies are chaotically located, the X ray diffraction patterns of disordered samples exhibit only characteristic of the cubic B1 structure. The vacancies are ordered during slow annealing from the temperature of the order-disorder phase transi tion; the crystal symmetry is lowered to monoclinic, so a Ti 5 О 5 phase is formed [3,4].Thus, the presence of vacancies and their ordering is energetically favorable for titanium monoxide. However, the role of vacancies in stabilization of the basic B1 structure is poorly understood.…”

mentioning

confidence: 99%

“…Their percent age can be up to 32 at % [1][2][3][4]. In the case of an equi atomic composition, the amount of vacancies is about 14-15 at % in each sublattice [3,4]. When the compo sition deviates from stoichiometric, the concentration of vacant sites increases in one sublattice and decreases in another [1].…”

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Role of structural vacancies in the stabilization of the basic B1 structure in nonstoichiometric titanium monoxide TiO y

Kostenko

Lukoyanov

Жуков

et al. 2013

Bull. Russ. Acad. Sci. Phys.

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Titanium monoxide TiO y is one of the few nonsto ichiometric compounds with a high concentration of structural vacancies in both sublattices. Their percent age can be up to 32 at % [1][2][3][4]. In the case of an equi atomic composition, the amount of vacancies is about 14-15 at % in each sublattice [3,4]. When the compo sition deviates from stoichiometric, the concentration of vacant sites increases in one sublattice and decreases in another [1]. The high content of vacan cies results in a wide homogeneity of titanium monox ide, which is in the range of y = 0.7-1.25 [3].Three stoichiometric crystal modifications of tita nium monoxide composition are known. They all have the basic B1 structure, but they differ from each other by the presence of vacancies and their specific loca tion. One can obtain a phase without structural vacan cies by annealing at high pressures [5]. At low pres sures, the thermodynamic equilibrium phases are those with vacancies. Vacancies may be located over sites of the basic В1 structure either randomly or in an ordered manner. The disordered state is thermody namically stable at temperatures above 1300 K, but it can be obtained at room temperature by quenching [3,4]. Since the vacancies are chaotically located, the X ray diffraction patterns of disordered samples exhibit only characteristic of the cubic B1 structure. The vacancies are ordered during slow annealing from the temperature of the order-disorder phase transi tion; the crystal symmetry is lowered to monoclinic, so a Ti 5 О 5 phase is formed [3,4].Thus, the presence of vacancies and their ordering is energetically favorable for titanium monoxide. However, the role of vacancies in stabilization of the basic B1 structure is poorly understood. There are many theoretical studies dedicated to this problem [6][7][8][9][10][11][12][13]. For example, the electron structure of the TiO and Ti 5 O 5 phase and disordered stoichiometric TiO 1.0 phase have been calculated in [12]. However, the ordered and disordered phases have been studied by various methods, which has made it impossible to compare their total energies adequately. In [13], only TiO and Ti 5 O 5 were considered. It was shown that a crucial role in stabilizing the ordered phase is played by oxygen vacancies; however, the reasons for the sta bility of the disordered state have not been considered. Thus, what the role of metal and nonmetal vacancies in disordered and ordered phase are remains an open question. This paper is aimed at determining the contribu tion of titanium and oxygen vacancies in the stabiliza tion of the basic B1 structure and to investigate the sta bility of crystal titanium monoxide modifications. To do this, we calculated the electron structures and total energies of the three phases: vacancy free cubic TiO, vacancy ordered monoclinic Ti 5 O 5 , and vacancy dis ordered cubic TiO y ; analyzed the features of the chem ical bond; and found the stablest crystal modification.The electron structure was calculated with the den sity functional theory and account f...

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Size effect on magnetic susceptibility of titanium monoxide nanocrystals

Валеева

Nazarova

Rempel

2015

Physica Status Solidi (b)

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For the first time a magnetic quantum-size effect is found in paramagnetic titanium monoxide nanocrystals with the sizes down to 30 nm. In situ measurements in the temperature range from 300 to 1200 K showed that the magnetic susceptibility of superstoichiometric titanium monoxide nanocrystals TiO y (y > 1) depends not only on the structural state of the sample, but also on the size of nanocrystals. The data analysis both for the ordered and disordered TiO y showed that the reason for inversely proportional dependence of Van-Vleck paramagnetism on the size of titanium monoxide nanocrystals is distortion of local symmetry of titanium and oxygen atoms near the nanocrystal surface. Van-Vleck contribution induced by the atomic-vacancy disordering in titanium monoxide is proportional to the deviation of the long-order parameter from its maximal value.

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Cited by 86 publications

References 13 publications

Development of a biomaterial based on HAP/TiOy nanocomposite with different stoichiometry

Development of a biomaterial based on HAP/TiOy nanocomposite with different stoichiometry

Role of structural vacancies in the stabilization of the basic B1 structure in nonstoichiometric titanium monoxide TiO y

Size effect on magnetic susceptibility of titanium monoxide nanocrystals

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