
%0 Journal Article
%A Lewis, R. A. 
%A Martin, A. D. 
%A Wang, X. L. 
%A Dou, S. X. 
%T Optical Investigation of La<emph tye="8">1-</emph><emph tye="8"><emph type="2">x</emph></emph>Ca<emph tye="8"><emph type="2">x</emph></emph>MnO<emph tye="8">3</emph> and La<emph tye="8">1-</emph><emph tye="8"><emph type="2">x</emph></emph>Li<emph tye="8"><emph type="2">x</emph></emph>MnO<emph tye="8">3</emph>
%J Australian Journal of Physics
%D 1999/04/28
%V 52
%N 2
%P 197-203
%K 
%R https://doi.org/10.1071/P98047
%U https://www.publish.csiro.au/paper/P98047 
%X An optical study has been made of La0&#183;7Ca0&#183;3MnO3 and La0&#183;8Li0&#183;2MnO3 in the infrared spectral region (100 cm-1 to 4000 cm-1). The transmission of all samples is negligible. The photoconductive response is also unmeasurable. The data reported are therefore restricted to reflectivity measurements. At room temperature, both materials exhibit similar &#8216;bending&#8217; and &#8216;stretching&#8217; phonon modes, associated with the MnO6 octahedra, at ~330 and ~580 cm-1, respectively. The &#8216;external&#8217; phonon mode observed at ~170 cm-1, corresponding to the (La,Ca/Li) cations beating against the MnO6 octahedra, is slightly shifted between the two materials, as would be expected on the basis of the different compositions. At elevated temperature (~600&#176;C) the intensity of the light reflected decreases across the infrared spectrum, and the &#8216;stretching&#8217; mode moves to lower energy. 
