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Ceramics with phase composition after firing in the range of 600 – 900 °C represented by anhydrous calcium sulfate CaSO4, and calcium sodium sulfates (Na0,8Ca0,1)2SO4 and Na6Ca(SO4)4 were obtained from a powder mixture of sodium sulfate Na2SO4 and calcium sulfate dihydrate CaSO42H2O, taken at a molar ratio CaSO42H2O/Na2SO4 = 1. The phase composition of the powder mixture after homogenization in a planetary mill in an acetone medium, in addition to the starting salts, also included hydrated sodium calcium sulfate Na4Ca(SO4)32H2O. When kept in water for 5 and 60 min the mass loss of ceramic sample fired at 700 °C was 15 and 75 % respectively. Ceramics in the Na2O–CaO–SO3 system in the form of granules or complex shapes obtained using 3D printing can be used as a removable (soluble or leachable) porogen and/or a prototype of a porous space with a given architecture when creating porous polymer or inorganic materials.

Abstract The effect of the pore size of macroporous ceramic materials based on β-Ca3(PO4)2 on their biological activity was studied. The formation conditions of macroporous ceramics with a porosity of >50% and a specified pore size were determined. The effect of components of the light-curing emulsion on the pore size in the final macroporous ceramics was studied. The biocompatibility of β-Ca3(PO4)2-based macroporous ceramics was demonstrated in in vitro biomedical assays. The effect of pore size of macroporous ceramic materials on mesenchymal stromal cell proliferation and viability was established.

Powders of calcium pyrophosphate Ca2P2O7 of γ- and β-modifications have been obtained using the thermal conversion of brushite CaHPO4⋅2H2O synthesized from phosphoric acid H3PO4 and calcium carbonate CaCO3 at a molar ratio P/Ca = 1.1. The resulting powders can be used to create various functional materials, including biocompatible and bioresorbable materials for the treatment of bone defects.

This paper studies the influence of lattice and shell type architecture on the mechanical properties of biodegradable polymer scaffolds (cellular matrices) designed to create structures for bone tissue engineering. Varying the topology of nodal connections makes it possible to control the relative rigidity of the metamaterial in the range from 0.004 to 0.123. It is shown to be possible to create permeable scaffolds using thermally extruded 3D printing based on polymers of different elasticities—polylactide and polyurethane. The use of “unit cells” of various types allows fabricating structures such as shells based on polylactide with a compressive strength of 1.5 to 19.7 MPa. Shells with a cubic type architecture based on polyurethane can be almost reversibly deformed at values of deformation of more than 50%. The developed approaches for obtaining polymer metamaterials and modifying their surface with calcium phosphate layer using an artificial interstitial fluid can increase the hydrophilicity of materials.

Calcium phosphate powder were synthesized from aqueous solutions of calcium lactate Ca(C3H5O3)2 and ammonium hydrophosphate (NH4)2HPO4 at a Ca/P = 1 molar ratio. According to the XRD data, the phase composition of as-synthesized powder consisted of brushite CaHPO4 ⋅ 2H2O and hydroxyapatite Ca10(PO4)6(OH)2. After heat treatment at 350–600°C, the powder was colored dark brown owing to the destruction of the by-product of the reaction. The composition of the powder heat-treated at 350°C included monetite CaHPO4 and hydroxyapatite Ca10(PO4)6(OH)2, and the powder heat-treated at 600°C consists of hydroxyapatite Ca10(PO4)6(OH)2 and γ-calcium pyrophosphate γ-Ca2P2O7. The phase composition of ceramic obtained from the synthesized powder after sintering at 1100°C consisted of β-calcium pyrophosphate β-Ca2P2O7 and β‑tricalcium phosphate β-Ca3(PO4)2. The colored after the heat treatment in a range of 350–600°C powders can be used as a starting for the molding of porous biocompatible calcium phosphate composite materials with the given geometry of the porous space by stereolithographic printing. The synthesized powder can be recommended for the development of biocompatible and biodegradable both ceramic composite materials and composites with polymer or inorganic matrix for bone implants.

Bone implants capable to create an electrical stimulus for bone tissue regeneration under the influence of an external magnetic field are considered. A promising method for generating local electric fields is the use of magnetoelectric (multiferroic) micro- and nanoparticles, being polarized under the action of an external magnetic field, creating electric fields comparable in amplitude to endogenous ones. Of practical interest are composite magnetoelectric particles consisting of a ferrimagnetic core and a piezoelectric shell brought into close mechanical contact. The paper presents the results of modeling the magnetoelectric effect in a composite particle, fabrication of composite particles with cobalt ferrite as a magnetostrictive core, and considers the issues of the chemical interaction of phases.

The review covers problems related to development and application of a new type of “smart” medical materials, mainly, for regeneration of bone tissue that are capable of creating additional stimuli influencing the regeneration process. Application of ferroelectric and magnetoelastic materials is discussed, including their use as sensors and actuators. Physical and materials science principles of development, along with examples of using composite magnetoelectric materials of the piezoelectric/magnetoelastic type as magnetically controlled scaffolds creating local electric fields, are analyzed.

Technologies for the 3D printing of metallic powders are being increasingly extensively used around the world as alternatives to casting and machining to manufacture components of complex shapes and prototypes. Silicon-alloyed aluminum alloys are the most widely used materials in the selective laser melting technologies, which is caused by the price of these alloys and their high manufacturability for the layer-by-layer fused deposition, owing to their low susceptibility to hot cracking under thermal and shrinkage stresses. High rates of cooling the melt facilitate the formation in the material of ultradispersed silicon-containing phases, which results in increased strength. In the article, exemplified by two cast alloys (AK7ch and AK9ch), the speeds of the process of building up the products by the selective laser melting technology have been determined at a laser-beam power of 300 and 325 W and an energy density within the range 89–32 J/mm3. It is shown that, for the AK9ch alloy, lower porosity values are achieved within the investigated energy density range when compared with the AK7ch alloy and better mechanical properties of the alloy with a higher silicon content are achieved within the range of lower laser-beam energy densities than for the alloy with a lower silicon content. The mechanical properties of the materials produced under the optimal selective laser melting conditions comply with the most stringent requirements for the mechanical characteristics of the castings of the AK7ch alloy upon heat treatment.

Ceramic in the system Ca2P2O7–Ca(PO3)2 was obtained by firing cement stone fabricated from a powder mixture which included β-tricalcium phosphate β-Ca3(PO4)2 and monocalcium phosphate monohydrate Ca(H2PO4)2 ∙ H2O. The molar ratio Ca/P of the initial powder mixtures was set as Ca/P ≤ 1. X-ray phase analysis shows all ceramic samples after firing at 1000°C to include β-calcium pyrophosphate β-Ca2P2O7, and a sample of the ceramic made from a powder mixture with the maximum content of monocalcium phosphate monohydrate Ca(H2PO4)2 ∙ H2O also contained β-calcium polyphosphate β-Ca(PO3)2. The obtained calcium phosphate ceramic with reduced firing temperature can be used to develop a resorbable matrix for tissue engineering structures.

Calcium phosphate ceramics, with the phase composition represented by β-calcium pyrophosphate β-Ca2P2O7, was obtained from a powder mixture of calcium hydroxyapatite Ca10(PO4)6(OH)2, monocalcium phosphate monohydrate Ca(H2PO4)2 · H2O, and sodium hydrogen phosphate Na2HPO4. The powder mixture was preliminarily homogenized in acetone using a planetary mill. This treatment resulted in the chemical reaction between the starting components to form monetite, calcium hydrogen phosphate CaHPO4 (precursor of calcium pyrophosphate Ca2P2O7). According to the XRD data, sodium hydrogen phosphate Na2HPO4 when present in an amount of 5 wt % in the starting mixture had no effect on the phase composition of the powder after homogenization and of the ceramics after annealing. Sodium pyrophosphate Na4P2O7 formed from sodium hydrogen phosphate Na2HPO4 as a result of thermal conversion had a significant effect on sintering mechanism and the microstructure of the ceramics. A ceramics with a low sintering temperature based on β-calcium pyrophosphate β-Ca2P2O7 was obtained for the first time from a powder system, upon preparation of which under mechanical activation conditions homogenization of components and synthesis of the main crystal phase precursor were combined.

Double calcium’ammonium pyrophosphate monohydrate Ca(NH4)2P2O7•H2O was synthesized as a result of the interaction of calcium carbonate, an aqueous solution containing pyrophosphoric and lactic acids, and ammonia. The synthesized powder turned black after the thermal treatment in a range of 500—700 °C due to amorphous carbon, which is a product of the destruction of the organic nature components present in the prepared powder. After the thermal treatment at 500 °C, the powder is amorphous to X-rays. The phase composition of the powder after the thermal treatment at 600 °C is presented by β-calcium polyphosphate β-Са(PO3)2, while β-calcium polyphosphate β-Ca(PO3)2 and tromelite Ca4P6О19 are observed after the thermal treatment at 700 °C. The calcium phosphate powder colored due to presence of amorphous carbon can be used as a photocured suspension component that increases the resolution in stereolithographic printing of pre-ceramic semifinished products with a specified geometry of the pore space of calcium phosphate ceramic matrices. The synthesized powder of double calcium’ammonium pyrophosphate monohydrate Ca(NH4)2P2O7•H2O can be applied as a precursor of biocompatible phases for the fabrication of calcium phosphate ceramics used in medicine for the treatment of bone tissue defects.

Macroporous calcium pyrophosphate ceramics with a pore size of 900 μm and a pore fraction of up to 65% demonstrating compressive strength of 5 ± 1 MPa were formed by DLP stereolithography 3D printing. Mixed sodium-calcium pyrophosphate CaNa2P2O7 was used as an eutectic additive in liquid phase sintering of the ceramics at 600–800 °C. Initial powder charge was selected from a mixture of Ca10(PO4)6(OH)2, Ca(H2PO4)2·H2O and NaH2PO4. The pH of the aqueous solution contacting with the manufactured pyrophosphate ceramics in the range (6–7.2) turns out to be acceptable for further biomedical tests as a bone grafting material.

A powder of monetite СаНРО4 with a particle size of 100–300 nm was synthesized from monocalcium phosphate monohydrate Ca(H2PO4)2 ⋅ H2O and calcium hydroxyapatite Ca10(PO4)6(OH)2 in an acetone medium upon mechanical activation in a planetary mill. According to X-ray powder diffraction data, after heat treatment in the range 900–1100°С, the phase composition of the samples was represented by calcium β-pyrophosphate β-Ca2P2O7. The synthesized powder can be used for producing resorbable calcium phosphate ceramic materials.

The results of studies concerning ceramics made of substituted (silver, zinc, copper, iron) tricalcium phosphate (TCP) powders are presented. It is shown that the pores in the obtained ceramics are interrelated, the size of macropores ranges from 200 to 400 μm, the size of micropores ranges from 1 to 5 μm, and there are nanopores between the ceramic grains. Such pore sizes can provide the penetration of biological fluxes and cells required for the subsequent formation and growth of new bone tissue into the ceramic matrix. According to the solubility in the physiological solution, the ceramics composed of cation-substituted TCP can be arranged in the following order: Ag ≈ Fe < Cu < Zn. According to the results of studies on the antimicrobial activity with respect to a strain of E. coli bacteria, it has been established that cation-substituted TCPs exhibit a pronounced antimicrobial activity. The highest antimicrobial activity has been shown by the samples of zinc-substituted TCP.

The mechanical characteristics are studied for macroporous composite implants on the basis of β‑Ca/PO4)2/polylactide and β-Ca/PO4)2/polycaprolactone obtained by means of thermal-extrusion 3D printing. The effect of the degree of filling exerted on the strength, Young’s modulus, and the characteristics of the material destruction is described for the polymer, as well as for the three-dimensional structure filled with phosphate cement.

An a priori approach for the analysis of the architecture of osteoconductive bioceramic implants has been proposed. The most permeable products have been achieved in the case of the Kelvin architecture and the gyroid. The promising implant architecture is chosen to be the Kelvin model with a porosity of 70% and the pore sizes of 750 μm. The permeability of this architecture calculated to be 987 darcy for water approaches the value of trabecular bone tissue. It is found that the most rigid model among the architectures studied is the model with diamond architecture, while the most compliant are the Kelvin model and gyroid.

A technique for colloidal forming of Ca2P2O7 macroporous bioceramics, based on low-pressure injection molding (LPIM) of a glycerol-water slip containing Ca2P2O7 and Ca(Н2PO4)2 into a plastic mold fabricated via FDM 3D-printing, was proposed. Chemical reaction between the solid phases of the water containing slip - Ca2P2O7 and Ca(Н2PO4)2, resulting in brushite (CaHPO4·2H2O) formation, led to consolidation of the casting and preserved its complex architecture in the course of mold burning-out. Macroporous ceramics of Kelvin structure (70% macropores with the sizes from 2 up to 4 mm), based on a pre-defined composition with 10 wt% Ca(PO3)2 and sintered in liquid-phase regime, demonstrated a compressive strength of 1.4 ± 0.1 MPa at a density of 22 ± 2%. In vitro tests on bioactivity in SBF solution, as well as on resorption of the ceramics in model solution of citric acid, were carried out., Graphical abstract Image 1, Highlights • A new method of calcium phosphate materials fabrication by using colloidal forming and 3-D printing was proposed. • In the course of sintering, incongruent evaporation of the calcium-metaphosphate-enriched melt occurs. • The maximum strength were observed for the ceramics containing 10 wt% Ca(PO3)2, sintered at 1000°C for 1 hour. • Hydroxyapatite nuclei after 24 h and layer after 120 h formation on the materials surface is observed.

Carbonated hydroxyapatite (CHA) owing to its chemical and phase composition that is similar to that of the inorganic component of native bone tissue is a promising material for reconstructive surgery to heal bone defects that are caused by trauma and extensive surgery. An original method for obtaining porous CHA ceramic granules was developed. To obtain a system of interconnected pores, a protein foam with sucrose was used. The optimum ratio of the protein foam to the ceramic CHA powder was found to be 3: 1 for production of porous ceramics with a homogeneous structure. The mechanical properties of the porous CHA ceramics that we obtained at different ratios between the protein foam and ceramic CHA powder were studied: as the concentration of the ceramic CHA powder increased in the mixture, the compressive strength of the CHA ceramics decreased from 6–7 to 2–3 MPa. The microstructure of the CHA ceramics is characterized by the presence of pores that are different in size, from fractions to tens of microns. In vitro studies of the porous CHA ceramics were performed. The evaluation of the influence of the granules on the growth of rat MMSCs in vitro revealed a decrease in the cell viability with an increase in the concentration of the granules. The reduced viability of the MMSCs in the presence of the granules can be associated with alkalization of the environment by the sintering additive.

X-ray amorphous powder was synthesized from a water solution of calcium acetate and a mixed-anionic $$ \left({\mathrm{HPO}}_4^{2-}/{\mathrm{CO}}_3^{2-}\right) $$ water solution, including ammonium hydrophosphate and ammonium carbonate, at room temperature without pH regulation. The powders synthesized from the mixed-anionic $$ \left({\mathrm{HPO}}_4^{2-}/{\mathrm{CO}}_3^{2-}\right) $$ solution can be recommended for fabricating composite materials with a polymer matrix or for obtaining ceramic containing tricalcium phosphate and calcite phases with firing temperature not exceeding 600°C.

Ceramic materials in the Na2O–CaO–P2O5 system have been produced using powder mixtures containing calcium hydrogen phosphates (monetite/brushite: CaHPO4/CaHPO4 ∙ 2H2O) and sodium salts (Na2CO3 ∙ H2O, Na4P2O7 ∙ 10H,O, and NaPO3). These salts were used as precursors to the following high-temperature phases: Сa2P2O7, Na2O, Na4P2O7, and NaPO3. The amount of the salts in the powder mixtures was such that the oxide composition of the ceramics corresponded to 10 mol % sodium oxide for each mixture in the Na2O–CaO–P2O5 system. The powder mixtures were prepared using mechanical activation in acetone, which was accompanied by monetite rehydration to brushite. X-ray diffraction characterization showed that, after firing, the phase composition of the ceramics produced from the powder mixtures thus prepared lay in the Сa2P2O7–NaCaPO4–Na2СaP2O7–Са(РО3)2 phase field. The resultant ceramic materials contain biocompatible and bioresorbable phases and can be recommended for bone implant fabrication.

Powder mixtures based on calcium hydroxyapatite (HAP) and sodium salts in the amount corresponding to 25 mol % of Na2O in the Na2O–CaO–P2O5 system were studied by isothermal exposures in the range of 600—1200°C. According to XRD data, the phase composition of the samples of HAP/Na2CO3 after calcination included HAP, β-CaNaPO4, and CaO. The phase composition of the ceramic samples from the HAP/Na2HPO4 powder mixture after calcination contained the phases of β-CaNaPO4 and Na4P2O7. The phase composition of the ceramic samples from the powder mixture of HAP/NaH2PO4 after calcination contained Ca2P2O7, Ca10Na(PO4)7, β-CaNaPO4, CaNa2P2O7, and Na4P2O7. The presence of sodium salts in the amount corresponding to 25 mol % of Na2O in the Na2O–CaO–P2O5 system provided the occurrence of liquid- phase sintering in compact preforms from the studied powder mixtures. However, the presence of the water-soluble salt Na4P2O7 in ceramic samples of HAP/Na2HPO4 and HAP/NaH2PO4 after calcination imposes a restriction on the use of such materials in contact with an aqueous medium. And the presence of CaO in the HAP/Na2CO3 samples excludes the use of such materials as bone implants.

Brushite (CaHPO4 · 2H2O) powder has been synthesized in aqueous 1.0 M solutions of calcium nitrate dipotassium hydrogen phosphate, and disodium hydrogen phosphate at a Ca/P ratio of unity, without adjusting the pH of the reaction. After synthesis and drying, the fraction of a reaction by-product (NaNO3, KNO3, or their mixture) in the powder was about 20 wt %. After firing at temperatures from 800 to 1000°C, the ceramics prepared using the powder synthesized from Ca(NO3)2 and Na2HPO4 consisted of β-Ca2P2O7 and β-NaCaPO4. After firing at temperatures from 900 to 1100°C, the ceramics prepared using the powder synthesized from Ca(NO3)2 and K2HPO4 consisted of Са10К(РО4)7 and СаК2Р2О7. The ceramic composites produced in this study can be recommended as materials for resorbable bone implants.

Brushite cement obtained from α-Ca3(PO4)2 and orthophosphoric acid in the presence of Mg(H2PO4)2 with compressive strength of 18 MPa was armored with a framework with the Kelvin architecture made of polylactide by thermoextrusion 3D printing. It is shown that armoring of cement with polylactide framework allows one not only to increase the compressive strength of such a structure (up to 35 MPa) but also to significantly improve its deformability (up to 15%).

The rheological properties of highly concentrated calcium phosphate suspensions for producing bioceramic with complex shape by means of slip casting and 3D-printing were investigated. Macroporous bioceramic with gyroid architecture was prepared by casting water slips into polymer molds with gyroid geometry, which were fabricated by thermal-extrusion and stereolithographic 3D-printing. The limitations of this technology in reproducing fine details as compared with direct 3D-stereolithography of ceramic suspensions are indicated.

Highly permeable macroporous implants of various architectures for bone grafting have been fabricated by thermal extrusion 3D printing using highly filled β-Ca3(PO4)2/poly(D,L-lactide) (degree of filling up to 70 wt %) and β-Ca3(PO4)2/poly(e-caprolactone) (degree of filling up to 70 wt %) composite filaments. To modify the surface of the composite macroporous implants with the aim of improving their wettability by saline solutions, we have proposed exposing them to a cathode discharge plasma (2.5 W, air as plasma gas) in combination with subsequent etching in a 0.5 M citric acid solution. It has been shown that the main contribution to changes in the wettability (contact angle) of the composites is made by the changes produced in their surface morphology by etching in a low-temperature plasma and citric acid. An alternative approach to surface modification of the composites is to produce a carbonate hydroxyapatite layer via precipitation from a simulated body fluid solution a factor of 5 supersaturated relative to its natural analog (5xSBF).

Calcium phosphate powder was synthesized from calcium formiate Ca(CHO2)2 and ammonium hydrophosphate (NH4)2 HPO4 with Ca/P ratio in the initial water solutions equal to 1. The phase composition of the powders synthesized from 0.5M solutions was represented by brushite CaHPO4 · 2H2O and octacalcium phosphate Ca8(HPO4)2 (PO4)6 · 6H2O. After firing at 1100°C the phase composition of the powder was represented by calcium pyrophosphate β-Ca2P2O7 and tricalcium phosphate β-Ca3 (PO4)2. The synthesized powder can be used to obtain biocompatible resorbable biphase ceramic materials and composites with a polymer matrix.

A calcium phosphate powder has been synthesized from aqueous 0.25, 0.5, and 1.0 M calcium lactate and ammonium hydrogen phosphate solutions atat a Ca/P = 1, without pH adjusting. According to X-ray diffraction data, the as-synthesized powder consisted of brushite (CaHPO4 · 2H2O) and octacalcium phosphate (Ca8(HPO4)2(PO4)4 · 5H2O). After heat treatment in the range 500–700°C, the powders were gray in color because of the destruction of the reaction by-product. The powders heat-treated in the range 500–700°C consisted largely of γ-Ca2P2O7. The ceramics prepared from the synthesized powders by firing at 1100°C consisted of β-Ca2P2O7 and β-Ca3(PO4)2.

The phase composition of brushite cement that is based on β-tricalcium phosphate (β-TCP) and monocalcium phosphate monohydrate (MCPM) is optimized. It is shown that an increase in the β-TCP/MCPM ratio from 1.0 to 1.35 leads to a 20% increase in the cement compressive strength. We assume that this is due to reinforcement of the cement with ceramic particles of β-TCP. Carbonated hydroxyapatite (CHA) granules that are introduced into the cement composition in the amount of 10 wt % also lead to a 20% increase in the cement compressive strength. The cement that is investigated is promising for use in osteoplastic surgery for healing of bone tissue defects that result from trauma and extensive surgery.

This paper examines the physicochemical properties and microstructure of brushite calcium phosphate cements possessing strength acceptable for application in surgery (15–20 MPa) and ensuring an optimal acidity (pH 6.5–7.5) of solutions in contact with them. Holding in a physiological saline produces significant changes in the microstructure of the cement relative to that before immersion in the solution: it causes a transformation of the most soluble components into platelike hydroxyapatite crystals.

On the basis of mixtures of Ca3(PO4)2(α-TCP)/CaO and α-TCP/CaMPO4 powders (M = Na, K), self-hardening pastes are prepared whose treatment with solutions of sodium bicarbonate and calcium chloride results in the production of chemically bonded composites containing the phases of hydroxyapatite (HA) and calcium carbonate, as well as TCP and HA. The resulting materials can be used both as relatively dense composites (up to 75%) for osteoplasty and in the casting of settable ceramic slurries in plastic molds of special geometry for obtaining osteoconductive macroporous ceramics.

Amorphous hydrated calcium phosphate powder was synthesized at room temperature from aqueous solutions of polyphosphoric acid and calcium acetate with addition of ammonia water solution. Synthesized powder remains amorphous after heat in the temperature range 200–500 °C. Phase composition of powder and compacted powder samples after firing at 800 °C consists of calcium polyphosphate (β-Ca(PO3)2), tromelite (Ca4P6O19) and calcium pyrophosphate (β-Ca2P2O7). Synthesis of amorphous hydrated calcium phosphate powder with the ion-exchange stage for preparing an aqueous solution of polyphosphoric acid can be recommended as a simple way of production of powdered precursor for biocompatible bioresorbable phosphate ceramics containing calcium polyphosphate, tromelite and calcium pyrophosphate.

Novel materials with a variety of properties, such as biocompatibility, antibacterial activity, interconnected porosity, and functionalities combined in one, are required for regenerative medicine. Porous β-tricalcium phosphate (β-TCP) ceramics doped with Cu2+, Zn2+, Ag+, and Fe3+ ions in the concentrations of less than 0.5 wt.% were synthesized and investigated. The obtained samples were analyzed by the diversity of analytical tools. The structure, solubility, and antimicrobial properties of the porous ceramics are shown to be very sensitive to the presence and the type of the cationic substituent. It opens the way to manage structure and properties of the materials for bone tissue regeneration by co-doping of the initial matrix simultaneously with different types of substituent ions.

Copper-substituted tricalcium phosphates (CuTCP) with different copper contents were developed using precipitation of copper-containing amorphous calcium phosphates (ACP) from salt solutions followed by heat treatment. Porous CuTCP ceramic was obtained using negative replicas. Using a set of investigation methods (powder X-ray diffraction, IR spectroscopy, ESR spectroscopy, and scanning electron microscopy), all copper-substituted tricalcium phosphates were found to have the whitlockite structure with copper incorporated in TCP in the 2+ oxidation state. The resulting material is promising for the use in regenerative medicine owing to higher solubility in body fluids compared with TCP and combination of bactericidal properties and the lack of cytotoxicity.

Porous ceramic, whose composition is mainly represented by calcium β-pyrophosphate β-Ca2P2O7, is prepared from a porous mixture containing synthetic calcium γ-pyrophosphate γ-Ca2P2O7 and milled 1-aqueous sodium dihydrophosphate in an amount from 2.5 to 40 wt.%. Ceramic sintering proceeds by a liquid-phase sintering mechanism due to melt formation in the system Na2O–CaO–P2O5. Ceramic microstructure after firing in the range 800 – 1000°C makes it possible to consider sodium polyphosphate not only as a component facilitating sintering by a liquid-phase mechanism, but also as an inorganic pore-forming agent.

Porous iron-substituted tricalcium phosphate (FeTCP) ceramics with a Fe content of 0.49 and 1.09% has been developed. The hydrostatically estimated ceramics porosity is 40–45%. The solubility of ceramics in an isotonic solution has been studied. The solubility rate of FeTCP ceramics is slightly higher as compared with iron-free ceramics. Based on the results of in vitro tests of FeTCP ceramics on cultured fibroblasts, these materials are believed to be biocompatible. The developed materials can be recommended for use in medicine in the treatment of diseases associated with bone lesions.

The properties of reaction-associated calcium-phosphate materials obtained by pressing paste based on α-tricalcium phosphate with subsequent holding in different solutions are presented. The phase composition, solubility and mechanical characteristics of the materials obtained are studied and biological tests in vitro are performed.

The use of citric acid, sodium pyrophosphate, and sodium tri- and hexametaphosphates is studied as additives intended to retard the curing of brushite cements for convenience of their osteoplastic use. The effects of these additives on the curing rates, microstructures, and mechanical properties of these cements are studied.

Mixed cationic Ca2+/Na+(Mg2+) polyphosphates, regarded as potential biocomposite fillers, were fabricated by solid-state reactions. Most of them demonstrated low solubility (assessed also by the Glasser and Jenkins approach) from 1 ± 0.2 g/L for Ca(PO3)2 to 5 ± 0.4 g/L for NaCa(PO3)3 and 50 ± 2 g/L for soluble phase of NaPO3. Liquid-state NMR of the soluble part of polyphosphates gave the degree of polymerization of their chains ranging from 10 to 30 for NaCa(PO3)3 and ca. 1000 monomeric units for NaPO3.

Incorporation of carbonate ions to the crystal structure of carbonated hydroxyapatite (CHAp) leads to the formation of point defects (vacancies) in Ca- and OH-sublattices as well as to microstrains revealed in CHAp nanocrystals. Various techniques, such as XRD, FTIR, TEM, FESEM/EDX, TG/DTA, AES (ICP), wet chemical analysis, Ca-ionometry, microvolumetric analysis of evolved CO2, BET adsorption, were applied to determine an efficiency of carbonate substitution, and to quantify the elemental composition, as well as to characterize the structure of the carbonated hydroxyapatite and the site(s) of carbonate substitution. It was shown that there is insignificant incorporation of Na into the crystal structure of HAp. Over the range of 0–4% wt. (x

CHA powder was consolidated without noticeable changing of its carbonate content using low-melting Na-Ca phosphate glass with the composition referred to 54% Na4CaP6O18 and 46% Na2CaP2O7 as a binder. A temperature window suitable for obtaining the composite was assessed as 450 – 475°C. The composites obtained at 450°C and 400 MPa for 1 hr demonstrate compressive strength up to 25 MPa.