https://personalpages.manchester.ac.uk/staff/j.gough/lectures/te/7_8_bone/BONE_ENG/ceramic/ceram1.pdf

Biphasic calcium phosphate nanocomposite porous scaffolds for load-bearing bone tissue engineering.

Crystal structure analysis of β-tricalcium phosphate Ca3(PO4)2 by neutron powder diffraction

Polarization of sintered hydroxyapatite (HAp) ceramics by application of an external dc field at higher temperature was analyzed by thermally stimulated depolarization current (TSDC) measurements. The mechanisms for the polarization and depolarization of HAp were discussed in relation to the instability of the protons in the hydroxide groups. The TSDC spectra consisted of broad peaks, while the ferroelectric substances such as the BaTiO3 ceramics exhibited a sharp peak. Although the maximum current density of 7.87 nA cm−2 for the HAp polarized at 400 °C under 1.0 kV cm−1 was approximately 1/12 lower than that of BaTiO3, the polarization charge of 14.9 μC cm−2 was almost twice as large as that of BaTiO3. Considering the activation energy of 0.72–0.89 eV for the depolarization, it was revealed that the polarization of HAp was ascribed to the migration of protons in the columnar OH− channels with a micrometer-order distance. It was also found that the polarization charge was large and long enough to enhance ...

Proton transport polarization and depolarization of hydroxyapatite ceramics

Calcium phosphate apatites with variable Ca/P atomic ratio II. Calcination and sintering

A study on the structure and energetics of hydroxyapatite has been carried out using generalized gradient approximation density functional theory. The previously proposed $P{6}_{3}∕m$ and $P{6}_{3}$ hexagonal structural models have been found to be energetically unfavorable as compared with the previously proposed $P{2}_{1}∕b$ symmetry and a newly proposed monoclinic $P{2}_{1}$ structural model. A detailed analysis of the symmetry restrictions and inconsistencies between the reported physical properties, such as diffraction and birefringence, with hexagonal symmetry question the validity of these models. Rietveld analysis carried out on a synthetic sample, reported to be predominantly hexagonal at room temperature, shows that the diffraction pattern of this material can be interpreted as a mixed monoclinic phase, 23% monoclinic $P{2}_{1}∕b$ and 77% monoclinic $P{2}_{1}$. This interpretation reconciles many anomalies in reported experimental observations.

Structure and stability of hydroxyapatite: Density functional calculation and Rietveld analysis

Thermal expansion of hydroxyapatite-β-tricalcium phosphate ceramics

PURPOSE:To obtain a block for manufacturing a denture with a bed by integral cutting which is excelling in processability, physico-chemical characteristics in an oral cavity and aestheric sense by providing shape, dimensions, quality of material and color arrangement the optimum in the manufacture of a plate denture with a bed to bind a crown part and a gum part beforehand. CONSTITUTION:In a plate denture with a bed by integral cutting using a block 1 for the upper jaw and a block 2 for the lower jaw, for example, a resin block can be manufactured as such provided with a plurality of color and material using a block produced by an integral molding at a high temperature, for instance, namely, the one with a higher level of polymerization having no non- continuous interface. This allows the avoiding of elution of a residual monomer from the part of a denture bed, exudation and adsorption of stinking material, discoloring and deformation and damage as well. In the plate denture with a bed is little in the elution of the monomer and excellent in the strength while being by far limited in the degrading of the plate denture part as caused with the passage of time. This also enables the manufacturing of the plate denture by integral cutting.

Block for cutting plate denture

PURPOSE:To easily obtain bioceramics having a low Young's modulus and hardly causing cracking when embedded in a bone in a living body by adding a specified amt. of Ti to tricalcium phosphate and carrying out granulation, molding and sintering at a prescribed temp. CONSTITUTION:Ti is added to tricalcium phosphate in 0.01-0.2 atomic ratio of Ti to Ti+Ca. The resulting powder is granulated, molded and sintered at 900-1,300 deg.C to obtain bioceramics. Since Ti is incorporated into a tricalcium phosphate sintered body having a high Young's modulus, a Ti-contg. tricalcium phosphate sintered body having a low Young's modulus can be produced. When the bioceramics is embedded in a bone in a living body, cracking due to the difference in Young's modulus between them can be inhibited over a long period of time.

Nakamura Satoshi

Papers

Thermal expansion of hydroxyapatite-β-tricalcium phosphate ceramics

Block for cutting plate denture

Bioceramics and production thereof