Amorphous Niobium-Doped Titanium Oxide for Thermal Stability

Solution Overview

Problem

Conventional low-E coatings with titanium oxide layers are not thermally stable after heat treatment, leading to film crystallization and thermal stress, which deteriorates the performance of the coating stack.

Innovation Solution

A low-E coating with a doped titanium oxide layer, sputter-deposited in an oxygen-depleted atmosphere to maintain an amorphous or substantially amorphous state, providing thermal stability and enhanced refractive index for antireflection and color adjustment purposes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional titanium oxide layers are sputter-deposited to achieve crystalline structure, then the refractive index is improved, but thermal stability deteriorates after heat treatment due to film crystallization and thermal stress

Engineering Contradiction:

Improverefractive indexVSAvoidthermal stability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent changes the deposition parameters by sputter-depositing titanium oxide in an oxygen-depleted atmosphere rather than oxygen-rich conditions. This parameter change results in an amorphous or substantially amorphous structure that maintains thermal stability during heat treatment while achieving the desired refractive index for antireflection and color adjustment purposes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs an oxygen-depleted atmosphere during the sputter deposition process. This modified atmospheric environment prevents the formation of crystalline structures in the titanium oxide layer, resulting in an amorphous phase that is thermally stable and resistant to crystallization during subsequent heat treatment processes.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Ease of manufacture

If titanium oxide layers are made crystalline to enhance optical properties, then antireflection performance is improved, but thermal stress increases causing deterioration of coating stack performance

Engineering Contradiction:

Improveantireflection performanceVSAvoidthermal stress

Core Design Contradiction:

Ease of manufactureVSStress or pressure

Solution Approach 1:

The patent changes the deposition parameters by sputter-depositing titanium oxide in an oxygen-depleted atmosphere rather than oxygen-rich conditions. This parameter change results in an amorphous or substantially amorphous structure that maintains thermal stability during heat treatment while achieving the desired refractive index for antireflection and color adjustment purposes.

Inventive Principle:

Principle #35Parameter changes

3Strength

If heat treatment is applied to the coated article, then glass substrate strength is improved, but coating performance deteriorates due to film crystallization and thermal stress

Engineering Contradiction:

Improveglass substrate strengthVSAvoidcoating performance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the deposition parameters by sputter-depositing titanium oxide in an oxygen-depleted atmosphere rather than oxygen-rich conditions. This parameter change results in an amorphous or substantially amorphous structure that maintains thermal stability during heat treatment while achieving the desired refractive index for antireflection and color adjustment purposes.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The amorphous doped titanium oxide layer ensures the low-E coating's stability during heat treatment, maintaining desired transmission characteristics and preventing deterioration of the coating stack's performance.

Implementation Method 1

the doped titanium oxide layer(s) is/are sputter-deposited in an oxygen depleted atmosphere so as to be amorphous or substantially amorphous

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 2

at least one infrared (IR) reflecting layer of a material such as silver, gold, or the like, and at least one high refractive index layer of or including doped titanium oxide

Methodology Applied

Scientific EffectInfrared reflection: Reflection

Data Source

PatentUS10479053B2Coated article having low-E coating with IR reflecting layer(s) and niobium-doped titanium oxide dielectric layer(s) and method of making same

Publication Date: 2019.11.19 GUARDIAN GLASS LLC

AI summary

A coated article includes a low emissivity (low-E) coating having at least one infrared (IR) reflecting layer of a material such as silver, gold, or the like, and at least one high refractive index layer of or including titanium oxide and at least one additional metal. A doped titanium oxide layer(s) is designed and deposited in a manner so as to be amorphous or substantially amorphous (as opposed to crystalline) in the low-E coating, so as to better withstand optional heat treatment (HT) such as thermal tempering and reduce haze. The high index layer may be a transparent dielectric high index layer in preferred embodiments, which may be provided for antireflection purposes and/or color adjustment purposes, in addition to having thermal stability.