Optical inhomogeneity of BaTiO3 thin films and its correlation with some deposition conditions

Pencheva, Tamara; Nenkov, Milen

doi:10.1016/s0042-207x(00)00194-9

Cited by 10 publications

(6 citation statements)

References 24 publications

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“…The optimal nanothin film is highly transparent in the wavelength range from 400 to 700 nm. The average transparency of the obtained nanothin film, shown in Figure 5, is about 87%, which is higher than the previous reported value in similar research, where, the average value in the range of 70-75% was reported [10,[12][13][14]. Moreover, homogeneity of the optical quality is evident in the spectrum of the nanothin film, which was prepared by our established method.…”

Section: Evolution Of the Preparation Methods And The Applied Optimizacontrasting

confidence: 51%

“…The great difference between the spectra presented in Figures 3 and 4 is due to the improvement made by our method. Figure 5 also indicates that the optical propagation losses of the prepared nanothin films are much lower than those of in the similar works [10,[12][13][14]. The optimal nanothin film is highly transparent in the wavelength range from 400 to 700 nm.…”

Section: Evolution Of the Preparation Methods And The Applied Optimizamentioning

confidence: 60%

“…Moreover, homogeneity of the optical quality is evident in the spectrum of the nanothin film, which was prepared by our established method. In other words, the spectrum of the optimal nanothin film did not exhibit successive maxima and minima, which have appeared in the spectra of the nanothin films prepared by other methods [12,13].…”

Section: Evolution Of the Preparation Methods And The Applied Optimizamentioning

confidence: 84%

“…Our results showed that the preparation conditions have a great effect on the reduction of synthesis temperature and time. It is interesting that our method is able to prepare multiple BaTiO 3 nanoscale products at a lower temperature as compared with the literature [12][13][14][15][16][17]. This property is another advantage of our established method.…”

Section: Improvements Made By the Proposed Methodsmentioning

confidence: 87%

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A new sol–gel processing routine without chelating agents for preparing highly transparent solutions and nanothin films: engineering the role of chemistry to design the process

Ashiri

2014

Philosophical Magazine

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The great sensitivity of titanium alkoxides to hydrolysis makes their sol-gel transformation very fast and thus difficult to control. A method was proposed to alleviate this drawback. Preparation of highly transparent solutions and nanothin films is another objective of the present research. Employing nanoemulsion method and optimizing the processing conditions, a clear solution of well-dispersed nanosized particles was obtained. With the proposed process BaTiO 3 precursor sols and nanothin films with enhanced optical transparency towards the visible were prepared. The optimal formulation of the sol consists of acetic acid, barium acetate, 2-propanol, TTIP and deionized water with 6:1:1:1:150 M ratios, respectively. It was found that the reduction of the temperature in the initial stage of mixing of precursors controls the size of the forming species and accordingly improves the stability and transparency of the sol. The results also showed that the applied modifications and optimizations significantly downsize the particles within the sol to the nanometric scale and accordingly result in a significant improvement in the optical response of the products.

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Section: Evolution Of the Preparation Methods And The Applied Optimizacontrasting

confidence: 51%

Section: Evolution Of the Preparation Methods And The Applied Optimizamentioning

confidence: 60%

Section: Evolution Of the Preparation Methods And The Applied Optimizamentioning

confidence: 84%

Section: Improvements Made By the Proposed Methodsmentioning

confidence: 87%

See 2 more Smart Citations

A new sol–gel processing routine without chelating agents for preparing highly transparent solutions and nanothin films: engineering the role of chemistry to design the process

Ashiri

2014

Philosophical Magazine

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“…3). The refractive index of these films is quite low n^= n i = 1.80±1.85 [14,15] and the compressive stress of 0.2±0.6 GPa is significantly smaller than that of the films passed through the temperature gradient (see above). The apparent low refractive index could not be caused by intermediate low-index layers (see Experimental) and is currently being investigated.…”

Section: ±1mentioning

confidence: 87%

Pyroelectricity in Highly Stressed Quasi‐Amorphous Thin Films

et al. 2003

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Spontaneous or stress-induced polarization, signifying pyroelectricity and piezoelectricity, respectively, can appear in ionic solids solely due to a non-centrosymmetrical spatial distribution of ions in a polar crystalline structure. Although theory does not impose strict limitations on the size of a polar crystallite, [1,2] the magnitude of pyroelectric and piezoelectric effects of some ceramics, particularly BaTiO 3 , rapidly decrease as grain size diminishes to a few nanometers. [1,3,4] Determination of the minimal number of periodically arranged unit cells for which a crystal retains pyroelectric and piezoelectric properties has become increasingly important due to the rapid incorporation of these materials into nanometer-scale devices. An intriguing complication to this quest arises from the fact that pyro-and piezoelectric effects may exist in structures that lack the spatial periodicity inherent for ionic crystals, but are composed of polar molecules with directional ordering. An example of such a material is a nematic liquid crystal. Spontaneous or stress-induced dipole ordering without fine-tuned positional order is theoretically possible in ionic solids [5] as well; however, only indirect experimental evidence supporting this theory has been presented so far.[6±9] The present work reports on the preparation and pyroelectric properties of quasiamorphous BaTiO 3 thin films that represent a polar ionic solid without spatial periodicity. Pyroelectric amorphous BaTiO 3 films were obtained by passing sputtered amorphous BaTiO 3 films through a steep temperature gradient. As-deposited BaTiO 3 films were stressfree (< ± 30 MPa) with refractive indices in the range of n^= 1.97±2.02, and a very small in-plane±out-of-plane birefringence of n i ± n^= ± (0.002±0.008), confirming film isotropy. A compressive stress of r e = 2.0±2.2 GPa developed in the films passed through the temperature gradient. The refractive index of these films decreased to n^= 1.89/1.94 but the birefringence grew to n i ± n^= 0.03±0.07, corroborating the existence of high in-plane compressive stress.X-ray diffraction (XRD) spectra of the films passed through the temperature gradient were indistinguishable from those of as-deposited films (Fig. 1a). No XRD peaks apart from those of the Si substrate were observed, indicating the absence of a crystalline phase. The volume detection limit of a crystalline phase by XRD calculated from the signal to noise ratio [10] was < 0.3 %. Furthermore, thorough transmission electron microscopy (TEM) investigation only rarely detected the presence of crystalline grains (Fig. 1b) [11] and the concentration of the crystallites estimated from TEM images was far below 0.3 %. In contrast to the similarity with respect to electron and X-ray diffraction analysis, as-deposited films and the films passed through the temperature gradient have distinctly different electrical properties. The films passed through the temperature gradient show a large pyroelectric effect p measured = (1±3) 10 ±9 C cm ±2 K ±1 (5±15 % that of...

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Nanothickness films, nanostructured films, and nanocrystals of barium titanate obtained directly by a newly developed sol–gel synthesis pathway

Ashiri

Nemati

Ghamsari

et al. 2014

J Mater Sci: Mater Electron

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Optical inhomogeneity of BaTiO3 thin films and its correlation with some deposition conditions

Cited by 10 publications

References 24 publications

A new sol–gel processing routine without chelating agents for preparing highly transparent solutions and nanothin films: engineering the role of chemistry to design the process

A new sol–gel processing routine without chelating agents for preparing highly transparent solutions and nanothin films: engineering the role of chemistry to design the process

Pyroelectricity in Highly Stressed Quasi‐Amorphous Thin Films

Nanothickness films, nanostructured films, and nanocrystals of barium titanate obtained directly by a newly developed sol–gel synthesis pathway

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