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Change of properties of thin films TSTS at a variation of pressure of working gas

The basic examinations were spent on the samples besieged at pressure of working gas 8 Ra. In such samples nuclear relation Zr/Ti corresponded ≈ 54/46. Drawing 3.5 reflects the characteristic changes

Microstructures of thin films PZT, otozhzhennyh on air.

Process of formation of a phase perovskita (Pe) in the low-temperature matrix of a phase pirohlora (Py) in the form of round (sferolitovyh) islets began at Totzh ≈ 550 0C (drawing 3.5,), differed stage growth (drawing 3.5,), and was terminated at Т01Ж> 600 0C (drawing 3.5. Otzhig samples in atmosphere of steams oksida lead led to decrease in temperature of formation of the Re-phase to values 540-550 0C.


C in the field of MFG sedimentation of films was carried out by the purpose of a variation of a composition at various pressures argonokislorodnoj intermixtures in a gamut 2-8 Pases. For crystallisation in a phase perovskita films otzhigalis at 600 oC within 1 hour.

At pressure decrease from 8 to 2 Pa the composition of a firm solution of films moved aside tsirkonata lead approximately on 2 % within field MFG, - on the phase diagramme this detrusion is presented in the form of a horizontal dashed line (drawing 3.6).

Drawing 3.6 Phase diagramme for thin films Pb (Zτ1.xTix) O3 in neighbourhood MFG: T - a tetragonal phase, Rli - romboedricheskaja a phase, M - a monoclinic phase [62]. Quadrates designate field of a variation of a composition of thin films at change of pressure of working gas in a gamut 2-8 Ra.

In drawing 3.7 dependences of an element relation of atoms Ti ∕ (Zr+Ti) (drawing 3.7,) and Pb ∕ (Zr+Ti) (drawing 3.7,) in films PZT ~ 1000 nanometers with growth of pressure of gas from 2 to 8 Pases are presented by thickness (all measurings of composition TSTS of stratums were spent in the fields which have undergone crystallisation in a phase perovskita). In the first case the curve represented dependence with the monotonous reduction of the content of atoms of the titan (drawing 3.7,). Thus most aloud slope was observed in the films besieged in a gamut of 2 4 Pases where phase crystallisation perovskita transited inactively, and at 6-8 Pases relation Ті/Zr in films was stabilised. As a whole, the diagramme testifies that a variation of pressure of working gas the composition of firm solution PZT in the field of MFG can be varied within 2 %.

Drawing 3.7 Change of a relation of atoms Ti ∕ (Zr+Ti) () and Pb ∕ (Zr+Ti) () at a variation of pressure of working gas.

Dependence Pb ∕ (Zr+Ti) with pressure growth represented monotonously increasing curve, which initial value (at 2 Pases) it was essential more low stehiometricheskogo a composition of firm solution PZT (Pb ∕ (Ti+Zr) = 0,93), and terminating exceeded stehiometrichesky a composition almost on 25 % (drawing 3.7,). From the diagramme it is visible, that a variation of pressure of working gas it is possible to change the relative content of atoms of lead in very wide interval of concentrations.

Change of a relation of atoms TiZZr and Pb ∕ (Zr+Ti) in the besieged film, most likely, is related to change of requirements of a thermalization of atoms Ti, Zr and Pb in argonokislorodnoj to plasma with growth of pressure of working gas. Calculations,

Spent for dispersion of atoms of metals in plasma of the inertial gases which parametres are close to the parametres realised in VCH ionnoplazmennom the discharge of installation, have shown, that character of a motion (direct or diffusion) atoms of metals (in our case - Ti, Zr and Pb) depends on their atomic weight, an atomic weight of used inertial gas, and also a geometrical arrangement of a band of erosion of a target and a substrate (drawing 3.8) on which yields of a pulverisation [142] are besieged. An argon Atomic weight (39,9 a.e.m.) it is closest to an atomic weight of the titan (47,9 a.e.m.), - therefore it is possible to figure, that already at pressure 2 Pases dispersion of atoms of the titan in plasma occurs intensively, and the dispersion mode is close to diffusion (the dispersion diagramme is presented in drawing 3.9 on the right). The diagramme of dispersion for heavy atoms of lead (207,2 a.e.m.) Has other, "extended" character, therefore in the standard geometry used in installation (at medial effective coal of sedimentation α ≈ 30 degrees), the relative degree of hit of atoms Pb on a substrate essentially more low, than for the titan. Dispersion of atoms of zirconium (91,2 a.e.m.) has the intermediate character (between the titan and lead), and with growth of pressure of working gas character of dispersion will come nearer to diffusion type. It means magnification of a share of atoms Zr in the besieged film (and, accordingly, reduction of a share of atoms of the titan, (drawing 3.7 see,). Similarly, at the further magnification of pressure there should be also a magnification of a share of atoms of lead (drawing 3.7,).

Thus, the made experiments show, that change of technological parametres of ionic-plasma sedimentation it is possible to change in rather wide limits as a relation of atoms Zr/Ti (i.e. to change a composition of a firm solution), and to change the redundant content of lead (in the form of it oksida) in a thin film.

Otzhig thin films on air at Totzh ≈ 600 0C has shown, that at low pressure of working gas process of crystallisation of a phase perovskita goes inconveniently (drawing 3.10, and,), that is related to the low content of lead in the besieged films. C growth of pressure of a gas intermixture observed growth

74

Drawing 3.8 Plan of a relative positioning of a substrate and a band of erosion of a target in installation VCH magnetronnogo pulverisations.

Drawing 3.9. The diagramme of dispersion of atoms of metals in plasma of inertial gases, according to [142].

Numbers of islets of a phase perovskita and volume occupied with them (drawing 3.10, in,). The full crystallisation of a phase perovskita in all volume to a film occurred at the pressure exceeding 6 Pases (drawing 3.10, d,). Dependence of magnification of a share of a phase perovskita with growth of pressure of working gas is presented in drawing 3.11.

The X-ray diffraction analysis of thin films (0-20) spent on samples, besieged at a variation of pressure of the gas intermixture, generated at various temperatures otzhiga, has shown, that at a room temperature

Drawing 3.10 Optical image of phase contrast (Ru/Re) of a surface of films TSTS besieged at a variation of pressure of working gas (2 - 8 Pases) and otozhzhennyh on air at 600 0C: 2 Pases, 3 Pases, 4 Pases, 5 Pases, 6 Pases, 8 Pases.

Pressure, Pas

Drawing 3.11 Change of the content of a share perovskita in the thin films TSTS besieged at a variation of pressure of working gas and otozhzhennyh on air at 600 0C.

To find out tracks of prospective monoclinic updating (drawing 3.6 see) it was not represented possible. In drawing 3.12 fragments of diffractograms of sprayed ceramic target PZT (drawing 3.12,) and the film by thickness of 1000 nanometers generated at TOTzh = 600░С at pressure of working gas of 8 Pases (drawing 3.12,) are given. On a reflex (200), to answering ceramic sample, it is possible to observe split of X-ray peak and

Drawing 3.12 Fragment of a X-ray diffractogram (a reflex (200)) a ceramic target () and films TSTS ().

To interpret it as superposition of two updatings of ferroelectric phases - tetragonal and monoclinic, the shape same

Reflex from a thin film does not allow to tell unequivocally - it concerns what updating of a ferroelectric phase.

Similar shapes of a reflex could be observed and on the films generated at other temperatures otzhiga and variations of pressure of working gas. Most likely, for revealing of a monoclinic phase in thin PZT films the equipment with bolshej resolving ability, than that which is reached on diffractometer ДРОН-7 is required.

3.3

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A source: Kanarejkin Alexey Gennadevich. Ferroelectric properties nanostrukturirovannyh systems on a bottom tsirkonata-titanata lead. The dissertation on competition of a scientific degree of the candidate of physical and mathematical sciences. St.-Petersburg - 2018. 2018

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