Rails: Open link in new tab (with ‘link_to’)

   The target: :_blank parameter should be a parameter of link_to, image_tag parameters

<%= link_to image_tag("facebook.png", class: :facebook_icon, alt: "Facebook"), "http://www.facebook.com/mypage", target: :_blank %>

Or with a block:

<%= link_to "http://www.facebook.com/mypage", target: :_blank do %>
<%= image_tag("facebook.png", class: :facebook_icon, alt: "Facebook") %> 
<% end %>

Follow this below command: 

<%= link_to image_tag("facebook.png", :class => "facebook_icon", :alt => "Facebook"), "http://www.facebook.com/mypage", :target => "_blank" %>