An effective route to the synthesis of carbonated apatite crystals with controllable morphologies and their growth mechanism

CrystEngComm ◽  
2015 ◽  
Vol 17 (29) ◽  
pp. 5422-5430 ◽  
Author(s):  
Juan Shen ◽  
Bo Jin ◽  
Yamin Hu ◽  
Qiying Jiang
Keyword(s):  
Growth Mechanism ◽  
Hydroxide Anion ◽  
Carbonated Apatite ◽  
Apatite Crystals ◽  
Phosphate Surplus

CHAp powders with controllable morphologies and sizes were synthesized using HMT as a hydroxide anion-generating agent in a phosphate-surplus solution.

Carbonated Apatite, Type-A or Type-B?

2011 ◽  
Vol 493-494 ◽  
pp. 293-297 ◽  
Author(s):  
Fu Zeng Ren ◽  
Yang Leng
Keyword(s):  
Hydrothermal Reaction ◽  
Type A ◽  
Precipitation Method ◽  
Apatite Crystal ◽  
Type B ◽  
Carbonated Apatite ◽  
Apatite Crystals ◽  
Carbonate Substitution ◽  
Human Enamel ◽  
The Comparative Study

Carbonated apatite, the basic mineral component in human hard tissues and an important bioceramic material, has been extensively studied. However, its atomic arrangements in apatite crystal structure and its experimental characterization are still not lack of debating. We analyzed infrared (IR) vibrational spectroscopy for carbonated apatite determinations, by comparatively studying the IR spectra of hydroxyapatite and of surface carbonate absorption, biological apatites (human enamel, human cortical bone, and two animal bones) and carbonated apatite. The carbonated apatite samples were sythesized by various methods, including precipitation method, hydrothermal reaction and solid-gas reaction at high temperature. The comparative study indicates that the bands at ~880 cm-1, ~1413 cm-1, and ~1450 cm-1 should not be used to identify carbonated apatite since they may result from carbonate absorption on surfaces of apatite crystals or separated carbonate phase present with apatite crystals. The IR characteristic bands of carbonate substitution in apatites should be: ν3 at ~1465 cm-1 for type-B (CO3 substituting for PO4) and ν3 band at ~1546 cm-1 for type A (CO3 substituting for OH). These signature IR bands are further confirmed by the ab initio simulations.

Montmorillonite Dendrites

1974 ◽  
Vol 32 ◽  
pp. 454-455
Author(s):  
Necip Güven ◽  
Rodney W. Pease
Keyword(s):  
Crystal Growth ◽  
Growth Mechanism ◽  
Growth Front ◽  
Morphological Features ◽  
Dendritic Crystal ◽  
Crystal Growth Mechanism

Morphological features of montmorillonite aggregates in a large number of samples suggest that they may be formed by a dendritic crystal growth mechanism (i.e., tree-like growth by branching of a growth front).

Structural phenomena in the growth of carbon nanotubes

1993 ◽  
Vol 51 ◽  
pp. 750-751
Author(s):  
Jun Jiao
Keyword(s):  
Carbon Nanotubes ◽  
Growth Mechanism ◽  
Carbonaceous Material ◽  
Cluster Growth ◽  
Structural Elements ◽  
Rich Variety ◽  
Different Shapes ◽  
Point To Point

HREM studies of the carbonaceous material deposited on the cathode of a Huffman-Krätschmer arc reactor have shown a rich variety of multiple-walled nano-clusters of different shapes and forms. The preparation of the samples, as well as the variety of cluster shapes, including triangular, rhombohedral and pentagonal projections, are described elsewhere.The close registry imposed on the nanotubes, focuses attention on the cluster growth mechanism. The strict parallelism in the graphitic separation of the tube walls is maintained through changes of form and size, often leading to 180° turns, and accommodating neighboring clusters and defects. Iijima et. al. have proposed a growth scheme in terms of pentagonal and heptagonal defects and their combinations in a hexagonal graphitic matrix, the first bending the surface inward, and the second outward. We report here HREM observations that support Iijima’s suggestions, and add some new features that refine the interpretation of the growth mechanism. The structural elements of our observations are briefly summarized in the following four micrographs, taken in a Hitachi H-8100 TEM operating at an accelerating voltage of 200 kV and with a point-to-point resolution of 0.20 nm.

Synthesis, performance and growth mechanism of silver nanoparticle coated SERS fiber probe

2019 ◽  
Vol 107 (3) ◽  
pp. 305
Author(s):  
Mengmei Geng ◽  
Yuting Long ◽  
Tongqing Liu ◽  
Zijuan Du ◽  
Hong Li ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Reaction Time ◽  
Growth Mechanism ◽  
Fiber Optic ◽  
Fiber Optic Probe ◽  
Visible Absorption ◽  
Fiber Probe ◽  
Surface Enhanced Raman ◽  
Optic Probe

Surface-enhanced Raman Scattering (SERS) fiber probe provides abundant interaction area between light and materials, permits detection within limited space and is especially useful for remote or in situ detection. A silver decorated SERS fiber optic probe was prepared by hydrothermal method. This method manages to accomplish the growth of silver nanoparticles and its adherence on fiber optic tip within one step, simplifying the synthetic procedure. The effects of reaction time on phase composition, surface plasmon resonance property and morphology were investigated by X-ray diffraction analysis (XRD), ultraviolet-visible absorption spectrum (UV-VIS absorption spectrum) and scanning electron microscope (SEM). The results showed that when reaction time is prolonged from 4–8 hours at 180 °C, crystals size and size distribution of silver nanoparticles increase. Furthermore, the morphology, crystal size and distribution density of silver nanoparticles evolve along with reaction time. A growth mechanism based on two factors, equilibrium between nucleation and growth, and the existence of PVP, is hypothesized. The SERS fiber probe can detect rhodamin 6G (R6G) at the concentration of 10−6 M. This SERS fiber probe exhibits promising potential in organic dye and pesticide residue detection.

VLS Growth of Si nanowhiskers on a H-terminated Si{111} surface

1998 ◽  
Vol 536 ◽  
Author(s):  
N. Ozaki ◽  
Y. Ohno ◽  
S. Takeda ◽  
M. Hirata
Keyword(s):  
High Pressure ◽  
Growth Condition ◽  
Growth Mechanism ◽  
Quantum Confinement ◽  
Critical Value ◽  
Extended Defects ◽  
Vapor Liquid Solid ◽  
Minimum Diameter ◽  
Vls Growth ◽  
Vapor Liquid

AbstractWe have grown Si nanowhiskers on a Si{1111} surface via the vapor-liquid-solid (VLS) mechanism. The minimum diameter of the crystalline is 3nm and is close to the critical value for the effect of quantum confinement. We have found that many whiskers grow epitaxially or non-epitaxially on the substrate along the 〈112〉 direction as well as the 〈111〉 direction.In our growth procedure, we first deposited gold on a H-terminated Si{111} surface and prepared the molten catalysts of Au and Si at 500°C. Under the flow of high pressure silane gas, we have succeeded in producing the nanowhiskers without any extended defects. We present the details of the growth condition and discuss the growth mechanism of the nanowhiskers extending along the 〈112〉 direction.

Chemical Availability of Bromide Dictates CsPbBr3 Nanocrystal Growth

2019 ◽  
Author(s):  
Je-Ruei Wen ◽  
Benjamin Roman ◽  
Freddy Rodriguez Ortiz ◽  
Noel Mireles Villegas ◽  
Nicholas Porcellino ◽  
...  
Keyword(s):  
Reaction Time ◽  
Growth Mechanism ◽  
Chemical Control ◽  
Critical Role ◽  
Phase Evolution ◽  
Detailed Understanding ◽  
Semiconductor Nanocrystal ◽  
Nanocrystal Growth ◽  
Chemical Availability

Lack of detailed understanding of the growth mechanism of CsPbBr3 nanocrystals has hindered sophisticated morphological and chemical control of this important emerging optoelectronic material. Here, we have elucidated the growth mechanism by slowing the reaction kinetics. When 1-bromohexane is used as an alternative halide source, bromide is slowly released into the reaction mixture, extending the reaction time from ~3 seconds to greater than 20 minutes. This enables us to monitor the phase evolution of products over the course of reaction, revealing that CsBr is the initial species formed, followed by Cs4PbBr6, and finally CsPbBr3. Further, formation of monodisperse CsBr nanocrystals is demonstrated in a bromide-deficient and lead-abundant solution. The CsBr can only be transformed into CsPbBr3 nanocubes if additional bromide is added. Our results indicate a fundamentally different growth mechanism for CsPbBr3 in comparison with more established semiconductor nanocrystal systems and reveal the critical role of the chemical availability of bromide for the growth reactions.<br>

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